I am MCS and get very sick when exposed to mold. Plus i have spring/fall allergies and can not take allergy medicine. When i wear them It helps block out strong smells, you might be able to still smell the smell, but its just not as bad (if you use the charcoal filters with them). I use the largest size my nose can hold, so i get the most air in. The white papery filter needs to fit exact or it wont block and protect you. I can breath fine in them and have worn them for really long periods at a time, as long as my nose doesn't run to clog them. I use them for a couple of days, clean them with alcohol wipes and pop a new filter in. They are hardly noticeable, people think i just have a nose ring in, but its much better than wearing a dusk mask! I wear them everywhere i go.
Only con i have is the white papery filter is maybe a tad too small because it easly gets pushed to the side and you lose protection...would be great if somehow it could stay in place....maybe bend up at sides and/ or fit a little snugger inside?

Im giving them 5stars because they are better than wearing a mask..i got lucky and got a size that i think fits..thers no open sides..sealed ..the only draw backs are miner...one is they make your nose look like miss piggy..not bad..but there not for fashion...two..is..if you have any kind of a runny nose they will clog up obviously..and three..is..if you dont wear them from the moment you walk out the door you nose will get full of crap anyway..i do lawncare and used them today blowing out leaves and i could see all the pollen that did get blocked on the screens..so i like them..they are not uncomfortable..and didnt hurt...they are pretty tinny but even with big fingers i was able to get them on and off..they actually open your nostrils up some and let air in better than without ..so i think they will be perfect for moutian biking on dirt trails..the order came with a bunch of sets..but unless your getting paint on them they wash out in the sink or a can air..

Whoever invented this nose filter system is a genius, and Woody provides great customer service too. I recently took a trip to Europe and between the long airplane flight and touring old cathedrals in need of mold remediation (lol), I was very glad that I made this purchase. I ordered an assortment package of 3 sizes in both shapes, slotted and round, and though I have small round nostrils, I felt that the small slotted frames felt the most comfortable. Once you have decided on the shape for the nostril frames, you have the option of ordering them fit with Ultra Breathable wire mesh in the frames, white Super Defense mesh, or a 3-in-1 combination of these two plus an activated carbon mesh. When ordering on Amazon, be sure to click near the three options shown to expand the menu showing all the many combinations. The scope of options can be a bit intimidating at first glance. It helps to keep in mind that you can order 4 different size frames with filters or just the replacement filters"”either in the Ultra, Super Defense, or the 3-in-1.

The Ultra mesh filters out pollen, pet hair and danger. The white mesh filters out dust, mold, and germs, and the black filters smoke, TVOC, and vehicle exhaust. The 3-in-1 combination is rated by the company as "good" in breathability, but not their "best", but neither my husband nor I felt that these inhibited our breathing over our 8 hour flight. More importantly, we both stayed healthy after sharing the recirculated, stale airplane air with others who may have been traveling with a cold or other virus. Later, a few steps into some of the old cathedrals reminded us that we needed our Woody filters. We didn't notice the moldy smell at all, so we were able to take our time enjoying all there was to see. These wonderful little filters are so inconspicuous and comfortable that the much more expensive mask I bought is still in its tin, unused. Whether you are allergic to pollen, cutting your lawn, or a traveler, you will be happy you have these Woody filters nearby. If this review helped, please leave a thumbs-up!

Updated to 5 stars;
I have been using filter from woodyknows from several years, they are great filters helped/ing me alot with allergies, I always used their older model; this year i tried the new model I ordered the same size as my older model, this model ended up being smaller than older model of the same size. I Expressed my proble in the review and went back and purchased the trusted older model. and forgot about it. yesterday, I got a email and that they will send me a filter that is bigger in size for free. Amazing Customer Service. I haven't really used the new model yet, but I know the filter will definitely work (I only had problem with size); and great company behind the product with best customer support you can get. regardless of this gesture, I would have been a lifetime customer of their products; this just proves the point.

Original Review:
Title: Smaller size than older models
I use to have a older model of the same size, that is a right size; i ordered this new model of the same size without going for the sample model . mistake, this one is smaller and falls off and will not hold. also the older model is like a nose clip and this one needs to be help by nostrils. anyways went back and brought the older model again.

This has changed my life! I am allergic to cats but I can't live without them. I was losing sleep from snotting and blowing my nose all night. Years ago I would shove kleenex up my nose as a filter. It worked but it was tickly and a nuisance. I started buying these Woody Knows filters a month ago and I haven't snotted since. Keeps the cat dander out of my nose. It works best for me when I change he filter every 2 to 3 days or it starts
to feel like I'm not getting enough air. It was difficult to change at first but it is easy now.