After years of using a cpap machine and hating the bulky mask and the claustrophobic feel of it, I saw an ad for the Snore Relief Mouthpiece. I thought, just another gimmick. But after another night of adjusting a leaky mask, I decided to order one. The mouthpiece was bogo. They arrived quickly and I used one that night. I had a great nights' sleep! It worked. I called my doctor and told him and he wanted me to do a sleep study because he was very skeptical. I did the study with the mouthpiece and passed with flying colors. I have not used my cpap since. It's so easy to take with me when I travel too. Thank you for this marvelous invention!