Written By: Kathy C, NC, US 9/10/2014
This is sold individually to be used between machine (especially if it is at an odd angle) and tube, but I use it on the other end, between tube and mask. They come that way on the Evo ComfortFit mask--my favorite--and make it easy to read in bed if you lie on your side. It bends in a way the tube does not. I love these and keep extras around to go with whatever mask I am using.
Written By: Art J., Bellingham, WA 12/15/2013
It does what it's supposed to do, but there was a faint whistling noise - probably from the flexible ribs.