Actually, you just breathe through the Accapella, but you have to be able to follow the directions and adjust the dial to suit your needs <img src=""> . I use my accapella (or my flutter, if I do it in the shower) when I am sick, in addition to the vest 2x a day. If I am only going somewhere overnight for 1 night, I just take my accapella, since I will be doing my vest once a day during that time- in the morning before I leave, and the next day in the evening when I get home.