hampers breathing small in size [SEP] the first time i used this it was hard to breath i have been wearing a mask hours a day for the last months i hoped this would help keep my mask from sweating to my face it does that but also makes breathing a bit harder not as much air circulation i thought it would help to increase air flow also they are very very small in length they do not fit from your nose to your chin they fall off your nose to sit comfortably i guess on your chin so in fact i am now messing with my mask all the time to try and keep it in place in a mask with a pocket i did revamp it by cutting out all the middle fins so i can breath i use these maybe twice a week not as effective as i had hoped