Works perfectly for PEX plumbing, the copper crimp rings fit very snugly before crimping, and the fittings are a little loose, but with sharkbite brand PEX tubing, its the exact opposite, and you are constantly struggling with keeping the crimp ring in place with that stuff. I used this for hot and cold water line in my trailer house and shop, AND for my air line in the shop at 150 PSI. Been over 6 months and not one single leak ANYWHERE. I will positively continue to buy this stuff instead of at the store.