yuwellAdult Oxygen Mask with 6.6' Tubing - Soft - XL Size - 10 Pack

As expected these allowed my wife to drop her O2 from 4l to 2l (mouth breathing),,,,,,,,,Not comfortable for 24/7/365 use but they do a great job of keeping oxygen focused to work through exacerbations when we are fighting to keep her O2 levels up