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NAROO Mask F1s & F5s Review

The past few weeks I have been trying a range of masks from NAROO Mask. This Korean-based company makes a range of sports-orientated masks for all kinds of needs – from UV and cold weather protection to fine dust filtering. 

Just last week I published an article featuring two masks from NAROO, the F.U+ and F.U+ Copper. These two masks are the more ‘standard’ masks from NAROO as they offer a traditional mask design with a piece of filtering media connected to ear loops. Today, I want to take a look at two more unique masks from NAROO – the F1s and F5s.

While these masks share some similarities with the F.U+ variants, they also have a few differences. The most obvious difference being the gaiter-like, neckband design. While all of NAROO Mask’s masks have been designed with exercise and sports in mind, these two particular models have some big differences that make them a choice worth considering for anybody who is more active. 

This post contains affiliate links. For more information, please refer to my affiliate disclaimer. I was sent a product for review, but the article is not sponsored. All opinions expressed in this post are my honest thoughts. I only recommend products that I genuinely believe in.

Information on this blog is for informational purposes only. Readers are encouraged to confirm the information herein with other sources. Furthermore, this information is not intended to replace medical advice from professionals. This website assumes no responsibility for the accuracy of the information, and information is subject to change without notice. Devices mentioned on this website are not medical devices and do not guarantee protection.

With that being said, today I want to provide my thoughts on both the F1s and F5s from NAROO Mask. These masks are largely similar, but they do have a few differences that will make them appeal to different audiences. 

If you’re interested in these masks but prefer a more traditional design, please feel free to check out my review of the F.U+. They share many of the strengths of the masks mentioned in this article, but they also use a more familiar mask design.

Before I dive into this review I want to put particular emphasis on two points:

  1. In this article I have provided my honest thoughts and experiences in regards to the fit of the mask. However, I cannot state whether or not the mask will fit you in the same way. Everyone has a different face and every mask fits differently. Unfortunately, the only way to see if a mask seals well on your face is to try it for yourself.
  2. The filtration lab results apply to the filter (not the mask) unless otherwise stated. To achieve a high level of filtration, it’s important to ensure that the mask is fitted correctly with no leaks. 

Now that those points are out of the way, I would like to introduce the F1s and F5s from NAROO Mask. If you have tried these masks yourself, please feel free to share your thoughts as a comment on this post. Hearing your experiences is invaluable for both me and future readers!

Save 10% on NAROO Masks with the code ‘Ethan2021’


Naroo Mask Micronet Filter

All masks in NAROO’s F-Series (F = filtration orientated masks) use the same filter. This filter is called the MICRONET™ filter and it is a design used exclusively by NAROO. Luckily, the filter is very capable. 

Most masks make use of a melt-blown filter. These filters are the standard in masks and what you will find in nearly all disposable respirators such as N95, KF94, and FFP2 respirators. They are also commonly used in reusable masks. The issue with such filters is that they rely heavily on electrostatic filtration – a filtration mechanism that becomes less effective over a matter of hours. 

Some other masks rely on nanofibre filter media. Nanofibre filters rely more on other filtration mechanisms and therefore retain filtration efficiency far better. On top of this, they often have higher filtration efficacies due to more consistent fibre placement and smaller fibres. 

The MICRONET™ filter is similar to a nanofibre filter except that it is created from microfibres rather than nanofibres. This means that it retains filtration efficiency very well even after being washed many times. However, it likely doesn’t filter ultrafine particles (0.3μm and below) as well as nanofibre filters used on the likes of Happy Masks.

Naroo Mask F1s 1

A third party laboratory in Japan has carried out filtration testing on the MICRONET™ filter. On particles within the range of 1.7μm – 2.6μm, > 99.9% filtration was observed across the tested samples. This particle range covers all PM10 particles and some PM2.5 particles, however, the tested particle range is substantially bigger than the standard 0.3μm particles used in the lab tests that most masks undergo. 

With this in mind, the filter is capable when it comes to larger particles. PM10, pollen, and other allergy-causing particles and larger PM2.5 particles will all be filtered at a rate of > 99.9%. With that being said there is no testing when it comes to ultrafine particles.

Perhaps the biggest appeal of the MICRONET™ filter used in the F1s and F5s is its reusability. Filtration testing was carried out after 100 wash cycles (the maximum test count offered by the laboratory) and the filter retained almost full efficiency filtering at a rate > 99.8%. 

Also worth noting is that ‘stretch testing’ has been performed on the filter. The filter will stretch quite a bit when worn, but even when stretched the filter achieved > 99.9% filtration efficacy against particles in the 1.7μm – 2.6μm range. 

The MICRONET™ filter on the F5s appears to be significantly larger than on the F1s. On The F1s, the filter media only covers about 1/4 of the mask. When worn, the filter covers my face almost completely. However, there are some small areas near the edge of my cheek where I wonder if air can pass through unfiltered.

In practice, I didn’t feel air passing through these areas. The vast majority of airflow was through the front filter, and I believe this is due to the low breathing resistance of the filter media. In saying that, I would like to see the filter size increased by a few centimetres on either side to ensure that it covers the full face of the wearer.

Save 10% on NAROO Masks with the code ‘Ethan2021’


Naroo Mask F5s Fitting

Both the F1s and F5s are masks that you put on over your head. They are full loops and function similarly to a gaiter mask except that they end just below the chin. This also makes both of these masks very unique when it comes to fit. 

While there are many gaiter masks out there, very few of them are designed specifically for filtering fine dust particles. Even fewer of these masks have filtration certifications or lab results. For this reason, both the F1s and F5s masks from NAROO have different fitting characteristics to most other reusable masks on the market.

Although both masks use the neck as one of the key fitting points (the tension created behind the neck will help to keep the mask in place), both masks incorporate ear loops. However, these ear loops don’t hold most of the pressure of the mask as they do on an ear loop only design.

Rather, the ear loops are there to keep the masks from slipping down the users face – something that can happen on neck-band based designs. I really appreciate this feature as I found the mask slipping less than other masks such as Purar and CosyPro.

When it comes to fit, the F1s and F5s are quite similar. However, I found three key differences that make the fit of each mask differ slightly. I first briefly mention the differences and then discuss how they apply to the difference in fit between the masks.

Firstly, the wire nosepiece on the F5s is significantly sturdier. Secondly, the ear straps on the F1s are added on the inside of the mask as opposed to being built into the mask itself as on the F5s. Finally, the F1s material is lighter and also is slightly more stretchable than the materials used on the F5s.

Naroo Mask F5s

I found that in regards to fit many of my thoughts reflect what I discussed in my previous review of the F.U+ and F.U+ copper. That is to say, the masks seal very well around the bottom of my face, but I have issues with leakage around my nose. 

I haven’t been able to fully remove leaks around my nose and I believe this is due to the wire being too sturdy – it’s hard to bend it to mould properly around my nose. This issue is exacerbated on the F5s where an even sturdier piece of wire is used for the nose seal.

What is interesting about the F5s is that while I can physically feel gaps in the seal around my nose, there is almost no airflow going up. When I breathe out, all of the air passes straight through the mask in front of my mouth. This is due to the fact that both masks are tight-fitting, and it appears as though a seal is created further down the mask, near the peak of my nose. On the F1s the leak is more obvious.

This may not be an issue for everyone as I do have quite an angled nose. However, this is what I have found while wearing the F1s and particularly the F5s. A potential remedy to this issue would be to add a piece of nose foam to the inner layer of the mask just inside where the piece of wire sits. 

In regards to stability and the masks ability to stay in place, both of these masks perform fantastically. Since the mask is kept in place by both the ear loops and the neckband, it easily remains in place – even when exercising. 

While it’s not perfect and it will need adjusting at times, I found it to need far less adjusting than nearly all other masks that I have tested. I tried it while skateboarding and I found that over the course of 3 hours I only needed to adjust it twice and this was largely due to the fact that I had to turn my head often to stay aware of obstacles and traffic.

Overall, both masks provide a sturdy fit that is likely to stay in place even after being worn for a long period of time. Both masks seal well around the bottom of my face, but both are loose around my nose. I did find the F5s to fit me significantly better and I noticed very little air flowing past my nose. I never had an issue with my glasses fogging on the F5s, but I did with the F1s.

Save 10% on NAROO Masks with the code ‘Ethan2021’


Naroo Mask F5s 1

While fit and filtration are more important in theory due to the fact that they directly impact how the mask will perform, comfort is just as important in real-world use. Although I have a large collection of masks, I nearly always find myself reaching for the mask that is easiest to wear when it comes to day to day tasks. For this reason, comfort is an often-overlooked yet very important factor when it comes to reusable masks.

Typically, there are a few aspects that I like to focus on in regards to comfort. Firstly, I like to look at the breathability and microclimate created within a mask. Both of these factors are very directly related, and a mask with low breathability tends to be very stuffy and humid inside. Further, I like to focus on the comfort of the mask in regards to the ear loops (or neck strap in this case) and filter interference with breathing.


F1s Netted Back

Netting at the back of the F1s.

Microclimate refers to the unique climate that occurs within the mask. If you’ve ever worn an N95, KN94, KN95 or equivalent respirator before you are likely already familiar with how hot and humid it can be within the mask chamber. This can lead to a lot of discomfort, especially in hotter parts of the world.

The microclimate within a mask is directly related to the breathability, airflow, and materials of a mask. While wearing the F1s I found the mask to provide a comfortable microclimate relative to other masks on the market. The filter is very breathable and allows for a lot of airflow.

The lightweight material used on the sides of the mask is also designed to draws out moisture from the wearer’s skin in order to allow it to evaporate. In practice, I did find the F1s to be comfortable even in hot weather. Of course, it was still very hot and humid within the mask but the temperature was significantly lower than I’ve experienced with reusable masks that use thicker filters and materials.

The F5s is a very different story. This mask is designed to be warmer than the F1s and is definitely better suited as a mask for colder seasons. The materials used are substantially heavier and the mask is much warmer. This is a mask that I will have to revisit in winter, but I see it being a great choice on cold days.


F1s and F5s Naroo Mask Filters

F1s and F5s filters.

The MICRONET™ filter’s biggest strength is its breathability. Both masks provide lower breathing resistance than melt blown filters but they have a higher resistance than nanofibre masks such as Happy Masks. What I found the most interesting is that the filters on both the F1s and F5s are harder to breathe through than the MICRONET™ filter used on the F.U+ and F.U+ Copper.

Initially, I thought I was just confused. However, after trying the masks side by side there is definitely less breathing resistance on the F.U+ masks. They both use the same filter media, so I am unsure as to what would cause this unless the filter on the F1s and F5s is thicker.

Even with higher breathability than the other NAROO Mask models both of the Gaiter-like masks provide an easier breathing experience than disposable respirators and many reusable masks that make use of replaceable filters.

Ear loops/Neck Band

F1s and F5s Naroo Mask

Ear loops/side view of F1s and F5s.

Typically this section focuses on ear loops, but with the NAROO Mask F1s and F5s ear loops are naturally less important as most of the mask’s pressure is placed on the wearer’s neck instead. With that being said, it’s important to discuss the comfort of both the ear loops and neckband.

Both masks are more comfortable than ear loop-based designs to wear for long periods. I often find my ears aching after wearing masks that rely on ear loops for fitting – something that I have not yet felt on either of the NAROO mask models. With that being said, the F5s does still place some pressure on my ears as the loops are far shorter and feel more weighty than those on the F1s. 

Both the F1s and F5s, rather, place more pressure on the wearer’s neck and (in the case of the F1s) use the ear loops simply as a way to keep the mask in place. While the F5s does place more pressure on the wearer’s ears, I found this to be far less irritating than masks that rely solely on ear loops.

The only time that I found the masks to be uncomfortable was when making large head movements. As I mentioned earlier, I wore both masks while skateboarding and when looking far left and right (for traffic and pedestrians) the masks would pull tight temporarily. This was a minor inconvenience, though, as these situations were generally far between and only for a short moment.

Filter Interference

Naroo Mask F1s Fitting

You can choose to cover your ears or not with the F1s.

The biggest issue that I found with both masks is the filter interference. When I talk about filter interference I am referring to whether or not the filter interferes with or makes breathing difficult. If you’ve ever ‘sucked in’ a mask, you will know exactly what I am talking about.

Since the NAROO Mask F1s and F5s sit so close to my face the filter sits on my lips. This is no issue in a normal situation where I will be breathing through my nose, but it can cause issues when I need to breathe through my mouth. It’s easy to ‘breathe in’ the filter and if I close my mouth the filter media will often be in the way.

This can be frustrating at times and can make it difficult to breathe when active. I was still able to exercise with the mask, but I would occasionally feel fibres from the filter in my mouth.

Save 10% on NAROO Masks with the code ‘Ethan2021’

Cost & Lifespan

The F1s comes in at a price of $43 while the F5s is considerably cheaper at only $30. In comparison, the F.U+ costs $20 while the F.U+ Copper costs $30. This makes the F5s price very comparable to many other non-replaceable filter reusable masks on the market. The F1s does have a premium, but it does have advantages – especially in summer when the cooler fabric makes a big difference. 

Mask ModelPrice
F.U+ Copper$30

The MICRONET™ filter used in all of NAROO’s F-Series masks has been tested and shown to retain > 99.8% filtration even after 100 wash cycles. This means that provided the mask is stored safely and handled with care, it should last for many months. 

Naroo Mask Fitting Dimensions

While there is no definite ‘end of life’ for either the F1s or F5s, NAROO Mask recommends that you replace the mask once it passes 100 washes. While the mask could theoretically retain filtration even further (the lab could only test for a maximum of 100 washes), there is no testing beyond this point. Further, masks tend to get clogged and breathing will become more difficult over time. 

If you do notice that the mask is substantially more difficult to breathe through than when you first purchased it, it is probably time to replace it. Masks can also begin to smell bad and have loose fibres over time, so if you encounter either of these situations a replacement may be in order. 

Personally, I tend to hand wash my washable masks every 3 or 4 days unless they get particularly dirty one day. At this rate, both the F1s and F5s would easily last around a year. However, without actually wearing the mask daily and washing it commonly myself, it’s hard to tell if it would need to be replaced earlier for other reasons.

Overall, the cost and lifespan of the F1s and particularly the F5s make them far more affordable than disposable masks in the long term. Even when compared to reusable masks with replaceable filters (such as Airinum or AusAir), these masks come in significantly cheaper due to their long-lasting MICRONET™ filter.

Save 10% on NAROO Masks with the code ‘Ethan2021’


Fitting Naroo Mask F5s

Both the F1s and F5s are strong additions to the lineup of masks from NAROO. They share many of the same strengths that the other F-Series masks from the company offers – high breathability, reusability, and comfort. Although my personal favourite mask from NAROO remains as the F.U+ Copper, I see both the F1s and F5s as being better suited for active lifestyles.

This isn’t to say that the F.U+ masks don’t perform well in these situations. However, I found that the fit of the F5s, in particular, was sturdy and this makes it great for exercising as there’s no need to be constantly readjusting the mask as I often find myself doing with other masks.

The biggest difference between the F1s and F5s is the materials that they are made from. The F5s is far too hot to wear in summer, and in the warm weather, the F1s is a more comfortable mask. I do see the F5s as being a good colder season mask, though.

The biggest issue with both masks is one that is shared with the F.U+ masks too. On all four NAROO Masks that I tested, I had trouble getting a good fit with no leaks around my nose. The F1s and F5s also have significant filter interference with breathing (especially heavy breathing).

I am unsure as to whether this is an issue caused by my facial structure, and as such, I would appreciate if anyone who has tried either of these masks could share their opinion. It’s hard to judge exactly whether or not a mask will fit most people, and your experiences are very valuable.

In conclusion, both the NAROO F1s and F5s are masks worth considering. As with every mask, they have flaws. However, they also offer a fit that makes them ideal for people with an active lifestyle. I am also a big fan of the filter and the high breathability that it has.

If you’re interested in learning about what other reusable mask choices there are, please consider heading over to this article on the best reusable masks.

Save 10% on NAROO Masks with the code ‘Ethan2021’

NAROO Mask F1s & F5s FAQ

Have the F1s and F5s Mask Been Lab Tested?

Yes. Both mask variants have had filtration carried out by an independent third-party laboratory.

Do the F1s and F5s Masks Have an Official Certification?

NAROO Mask has official test results, but no official filtering grade (such as N95, KN95, KF94, etc).

Should I Buy the F1s or F5s?

The biggest factor to consider is the difference in materials – the F1s is significantly lighter than the F5s is, therefore, makes for a much better mask in warmer seasons or locations. The F5s, on the other hand, is a good choice for usage in colder climates.

What Are Some Alternatives to NAROO Mask?

If you are looking for reusable masks without replaceable filters Cambridge Mask and Vogmask are two popular choices. Here is a list of even more alternatives.

Read 4 Comments on 'NAROO Mask F1s & F5s Review'

  1. Hey Ethan,

    Dang, love your work! This was an exceptionally comprehensive and well-researched review, thank you for the valuable info!

    I actually have an F1s in my cart on the Naroo website right now (with your voucher code successfully applied!!), but I am having second thoughts about the sizing… As a 165cm (62kg) caucasian female who usually wears size 10-12 clothing (Australian sizing) and who has a small head, I tend to opt for S-M mask options. However, the Naroo sizing guide puts me in the L-XL category. Which is absolutely fine, but some corroboration from other consumers if the sizing runs small would be reassuring! Particularly because the description of measurement 2 (“from the bridge of the nose to the back of the head”) does not correspond to the picture which shows from the bridge of the nose to above the ear.

    My measurements are as follows, which size did you end up using?
    (1) Anything from 19 – 21cm depending what you classify as the “bottom of the neck”.
    (2) 24cm from the bridge of my nose to the middle of the back of my head.

    Finally, I have previously purchased Aviro masks (which I love) in size S-M and they fit beautifully. Based on the sizing guidelines here it would seem quite possible that an L-XL Naroo would be the correct fit.

    Thanks again for your reviews!

    1. Hi,

      Thanks so much for your feedback! I really appreciate it.

      I have the F1s in small (well, the box says ‘slim fit’ which I assume is the S-M size) and I am a male at 175cm and about 65kg. The S-M is slightly too small for me. My girlfriend, who is about 160 found the S-M to fit very well. Base on that, I would say that an S-M or M-L would probably be the best fit for you. The material is very stretchy (and is designed to be stretched) so the device can become a bit bigger than it is initially.

      I hope this helps!

  2. Ethan, I really admire your thorough coverage of the various mask options out there. But after buying the F1s I am a little disappointed. I bought it to wear while playing racquetball (think squash) and it was excellent. Great fit, easy breathing, the perfect solution. Until I delved deeper and reread your review. It’s clear that it doesn’t filter out covid particles at all. Unless you believe as some say that covid particles are always hitchhikers are larger particles. You wrote: “On particles within the range of 1.7μm – 2.6μm, > 99.9% filtration was observed across the tested samples. This particle range covers all PM10 particles and some PM2.5 particles, however, the tested particle range is substantially bigger than the standard 0.3μm particles used in the lab tests that most masks undergo.” This seems to indicate that the F1s is NOT an adequate covid prevention mask. But in a recent post by the Aerosol Laboratory of the University of British Columbia, they view the filtration efficiency of any “Well-fitted mask with decent filtration efficiency” to offer filtering of particles from 2-8 microns. I’ll settle for decent if it lets me play racquetball. What is your view of this?

    1. Hi Jack,

      Thank you for your kind words! I am happy to provide my thoughts on your question, but please keep in mind I am no expert, and these are just my thoughts.

      Generally, masks can filter smaller particles than those they are tested against due to the MPPS ( However, this occurs around 0.3μm and, in the case of the NAROO Masks, doesn’t apply. With that said, if the mask is fitted correctly, I would guess it provides better or similar protection to a loose-fitting KF94 or equivalent mask. Of course, a well-fitting N95 will provide significantly more protection.

      If COVID is your biggest concern, I would recommend moving to another breathable mask with higher filtration.

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