Very convenient to use in all of your masks that have a pocket. The carbon filter is flexible enough that it slides right into the mask and it is very easy to breathe through.
We replace these probably less than we probably should but it's only b/c we don't use our masks very much/often since we never go out lol.
Done well with them.
I have been using these masks since March for sometimes 10 hours a day at work, and I am impressed with how they have stayed in perfect condition while being extremely comfortable and not-suffocating. I have only had to replace two nose bridges so far, and that is with constant washing in hot soapy water. Overall very happy with my purchase!
The adhesive on nose bridge is not good. Not sure what constitutes good design but should be non-threading to nose ,soft and pliable but retains shape