I have a very expensive dental device ($1800) for sleep apnea that broke after 1 year and is being repaired. It kept me from snoring. While its being repaired I tried this device and quite frankly it works just as well as the dental apparatus. It looks small when you take it out of the package but like someone else who provided a review I grew up playing sports and had to have mouth pieces like this every year, You just need to be careful when molding it to your teeth, You must spread the sides wide enough to place it in your mouth, then finish molding it . Also be careful not to bite down very hard and collapse the spacing between top and bottom. I am 65 weigh 230lbs and have a large mouth, because of my experience in sports I had no problem, Im actually glad its so small it makes it less invasive. I gave it 4 stars because the instructions did not address the molding process very well. As far as performance its definitely 5 stars for the money it cost!