Fine, it's a bit bulky even compared to a double layered buff but doesn't impede my vision as much thanks to the nose wire. I can breathe easily for the same reason i can breathe if i don't wear a mask at all - there is nothing to impede breathing since the mask is open at the bottom. That is also the reason I am very concerned about other people using it at gym, and you actively marketing it for that purpose. This mask is in no way suitable for indoor use, and you are being incredibly irresponsible in suggesting that it might be. That is the reason i am giving you one star only - it would be irresponsible of me to be seen to be endorsing this mask, given how you are marketing it.