The mask has a very good fit for me. I have a number of other KF94 masks - and not all of them fit as good as this one. This mask is very breathable - despite the exceptional fit - and I know that I am also very well protected. I think that most recommend changing out these type masks every 10 hours of use. As I don't tend to be indoors in public places (grocery stores, etc) for extended periods of time - I am able to use the mask multiple times, until it is time to change to a new one. Gordon Lavoie, Prince Edward Island, CANADA