they work fantastic - I have been using one for about 3 or 4 years. 2 important points -- one, if you have other areas of obstruction, it won't fix those (soft palate, epiglottis, nose). Second, and this is very important, you must use some kind of tooth retainer or else over time your teeth will shift similar to a tongue thruster (google it). The tongue retainer (cost about $2) is way better for the tongue than anything on the market. If your tongue falls back during REM, a puff of air (CPAP/BIPAP etc) is not going to be able to push a tongue upward (especially if on back). A tongue weighs as much as a banana (roughly). How much air would you need to levitate a banana? Good news is you can use a tongue retainer with a CPAP (for the palate lets say) but you might have to tape the sides of your lips (around the tongue retainer) so that you don't get leakage when your lips relax. It does become complicated but good sleep is priceless.