A CPAP chin strap like this is a great CPAP accessory. CPAP chin straps are used with nasal CPAP masks to help keep the mouth closed and prevent mouth breathing. People who use nasal CPAP masks are supposed to breathe only through their nose during the night, and this chin strap is great for people who have trouble doing so.
There are 2 different types of CPAP chin straps to choose from: Universal Adjustable and Neoprene. The Universal Adjustable CPAP chin strap can be adjusted at multiple points to help you find your best fit. The Universal chinstrap is available in 2 sizes: large and regular. The Neoprene chinstrap is hand washable and provides a secure, comfortable fit. Both CPAP chinstraps come up to the back of the head to keep the mouth closed.