Chin Straps are designed to hold your chin comfortably and keep your mouth closed while you sleep. This lessens air leaking which will dry out your nasal and throat passages, and encourages breathing through your nose. These include: a dry mouth or the feeling of air bubbling through your lips as you go to sleep. Chin straps can also sometimes help prevent air swallowing (aerophagia) and the discomfort it causes. There are notably fewer problems with the material stretching out.
(click to open image in new window)