I purchased this muffler for use with my ResMed AirMini machine. The problem I was having was the machine 'sounded/felt' like a dentists drill in/on my head, it was hard to sleep with it. Through some research and testing myself - this set up fixed that problem for me - I run the AirMini, an adapter to a 18" tube, to this muffler, to a SLIMLINE hose, and then finally my ResMed AirFit F20 mask. This combination make my machine 'sound/feel' as quiet as my home machine! It did not work as well if I used a normal size tube to my mask - it has to be a slimline to work best for me. Because it works for me, (and your mileage may vary) I would recommend it. Seems good quality to me, it works, and is the right diameter for my tubes to seal well and have no leaks.