This is definitely one of the best defogging products on the market for your scuba mask. The 500 psi defogger is thick and a little bit goes a long way. Unlike other products on the market that are very thin and easy to overuse. One 2 ounce bottle of 500 psi is enough to last most divers for years. The convenience of a clip-on design bottle which allows us to clip it on to the inside of our dive bag, duffel bag or backpack so we never forget it.