Terrible!
Trying to sleep in this was a nightmare. The part of it that goes under your soft palette is way too thick and it pushed my tongue back making me feel like I was on the verge of gagging. I had to consciously keep my tongue forward. Not ideal when you're trying to sleep. I also felt it was hard to breathe without keeping my mouth open. Lastly, each time when I started to clench/grind in my sleep, I woke up with pain and the pain was concentrated on the front teeth since that's all it covers. It seems that it would be better if it were an evenly distributed force over all teeth instead. Anyway, half way through the night, I had to take it out to get some sleep. I don't recommend this product.
Rating: 1 stars