"I suppose any oral device takes some getting used to. This is a device that uses a suction bulb to keep the **** forward position. It says not to cut the device in anyway but I just had to trim it to fit my mouth better. I couldn't get past the soreness on my bottom gum line. Once I made that very small adjustment it became comfortable after a few nights. I use invisaline as well and that doesn't affect the use at all. I will keep using. "