"Trying to size my cpap hose, I bought this ring, but it came with no instructions. So at first I was trying to figure out how I was supposed to measure the distance between my nostrils, then finally I realized this device didn't do that, it only sized the size of your nostrils. Which seems odd, since someone could have smaller nostrils, but they could be further apart. I would assume distance was a more important factor than size. Anyways, this really need some instructions, and possibly a second measure for distance."