The PMV^® 2000 (clear) (15mm I.D. 23mm O.D.) is lightweight and opens with even less resistance than the original Passy-Muir^® Valves. Its clear design and lower profile offers less visibility for the more ambulatory patient, although it can also be used in-line with mechanical ventilators in conjunction with non-disposable, flexible tubing, such as a 22mm silicone adapter.