The Czech M10M is the one mask that I have put more time into in the last 6 months than any other mask in my life, so far. It cost just under $40 on eBay for the mask, filters, bag, and drinking caps for a canteen. I have used this mask for exercise, for training, and just to wear it and see what it would be like to live out of it. I am going to share my experiences of the last few months with you and let you decide if this mask has the right stuff for your needs. OLD MASK WARNING The Czech M10M is a copy of the old US M17 mask, but with some minor differences that I will not discuss here. This mask was made for Czechoslovakia during the Cold War and was stored for a very long time. The mask I have is one year older (made 1988) than I am, and I assume the filters would follow that age. No one should get this mask with the idea that it is going to protect them from chemical or biological threats. However, they can still be pretty effective against aerosols like gas, smoke, etc. Make sure you really take the time to clean these masks out before using them as some of the powders used for preserving the rubber may not be very healthy to breathe in. PARTS OF THE MASK The M10M is the designation for the latest variant that has a drinking tube installed. The drinking tube wraps around the entire front voice diaphragm/exhale valve system, and is covered by a rubber sheath. The canteen attachment plugs and snaps into a rubber mount, making it low profile and a neat little package. The chin, mouth, and nose are isolated in the mask by a flimsy rubber face cup, and you have only two small one-way valves that feed you air when you inhale. These valves in my face cup are flimsy and do not reliably seal, causing the lenses to fog up relatively easy. In front of the face cup valves are slits just behind the lenses that use some of the inhaled air to defog the lenses before getting to the face cup valves. I have found these to be very useful. The eye pieces are a two-piece design that were separate when I got the mask. There’s the base eye piece made into the mask, and then a clear protective piece that I got with the mask that fits over and secures with a built-in rubber seal. I will tell you that they are a pain in the ass to put on without marking the inside of the lenses with fingerprints. Luckily they have little marks on the mask and the eye pieces so you line them up properly. The filters are triangular and had to be installed when I got the mask. This was a bit of a pain to work the rubber just right in order to fit the filters in either side without tearing the mask. They are installed from the inside and secured by the filter valves and two plastic buttons that hook through the rubber flap covering the back of the filter, inside. The filters make your cheeks very large and make it difficult to get behind sights on shoulder fired guns. The filter valves are threaded directly to the filters and hold them in place. Each valve has a paper-thin one-way rubber seal that allows air to enter when you create a negative pressure by inhaling. The voice diaphragm on the M10M is pretty large and seems to work okay, though I tend to sound like I’m whispering when I stand more than 5 feet away from my camera and talking with a slightly raised voice. This means I basically need to yell in order to have a normal volume that my camera can pick up on. The exhale valve is a small one-way rubber seal on the front is below the voice diaphragm. It is not only shielded, but has a redundant inner valve that is identical in size and design. This may have been necessary to balance there being two inhale valves (one on each filter). One exhale valve may not have proven to the designers to be enough to sustain the negative pressure created by inhaling. There are 4 adjustable elastic straps and 2 hard webbing straps connected to a rubberized backing. The 2 top straps are adjustable, but are meant to be set to a certain setting and left there. The elastic straps have rubber tabs on the end that you pull on in order to tighten the mask and seal it properly. I like to center the rubber pad on the back of my head perfectly with the bottom arrow touching the back bump where my skull and spine come together. HOW IT WORKS Let’s quickly explain how this system works when you are breathing, using all the parts I just pointed out. You create a negative pressure inside the mask by inhaling, which seals the one-way rubber exhale valves tight. Air gets pulled in through the two filter valves, gets processed through the two filters, comes up through the lens defogging channels or around the face cup, and finally gets through the face cup valves and into your lungs. When you exhale, all the air in the face cup is sealed most of the way by the face cup valves and completely sealed by the filter valves, leaving only the exhale valves for the air to escape. Then the cycle repeats itself once you inhale again. DON & CLEAR TECHNIQUE Unlike other masks that have inhale/exhale valves that can be blocked for a standard don & clear technique, the Czech M10M exhale valve is protected from being blocked. Because of this, the only way I know of clearing the mask is to: 1. Hold the head straps up and force your chin and nose into the face cup. 2. Pull the straps over your head and then start tightening them with both of your heads. Make sure you are pulling equally on both sides. Ensure that the face cup fits securely all around your nose, mouth, and chin. For the best seal, you will have to have a freshly shaved face. 3. Block the filter valves with your palms and try to suck in. 4. Let out a long exhale while simultaneously pushing the filter valves in against your face sharply multiple times. Be sure to take your palms off the filter valves between each pump. This pumping action is done to try and force the contaminated air outside the face cup to enter the face cup and be expelled with the rest of your exhaled breath. You won’t get all the air in one pump, so consistently exhaling and pumping several times will force filtered air in to help dilute the contaminated air and also carry it through the face cup valves during follow on pumps. You will know you are doing it right when you feel air breezing lightly on your eyes and on the tip of your nose. WORKING AND TRAINING Working in the mask is fairly simple. It is lightweight and doesn’t mess with your neck very much just to wear it while going about your daily activities and chores. I had to practice putting it on just right so that I could wear it comfortably for a long time. Unfortunately, the best I have done without a break is 2 hours. The eye pieces feel like they are pushing against your head and trying to smash your skull slowly after about an hour, which can drive you nuts when you are really trying to focus and concentrate. Despite this mask having two eye pieces, the vision is not all that bad. I have a good amount of peripheral vision, but I cannot see down right in front of me very well, leaving it to my feet to feel around. The depth perception in this mask is slightly skewed within arms distance, making it difficult to judge distances and interact with objects effectively when looking straight at them. I found it best just to choose an eye to do a task with, and accept the imperfect depth perception instead of conducting a futile struggle to acquire depth perception during a task that truly does not need it. When you start really needing air, this mask is comparable to you just breathing out of your nose. It does not give you much air right away, but it is not enough of a strain to do heavy workouts in this mask. When you start sweating in this mask, you can definitely feel the tension build on your face where the mask holds a seal. It is like the sweat builds around your face and makes the mask fit a bit tighter as a result. When you are in the mask for a while, the voice diaphragm and inside of the face cup will start building up humidity. This in turn will leak out of your exhale valve as you breathe, resulting in drops falling on yourself or the floor. This is just something I noticed from prolong wearing. MY PERSPECTIVE In my opinion, this mask is very good for working out and developing a robust pulmonary system. It is not so good for handling long guns or anything that needs to be aimed from the shoulder. The cheeks don’t stick out too far, but they are large enough to prevent me being able to look down and have full downward range of motion with my head. This is not a serious handicap, but one that has played with my mind at times. Overall, it is a good value for around the house usage and for working out. I can think of several things that cost way more and will give much less return in the long run.
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