Last Thursday we got 2 brand new 30lb cylinders of R134a. I put one on our AC machine and the other one in the closet. I charged 1 car Friday. Today I went to charge a car and the bottle on the machine was empty! So I brabbed the other one. It's empty too. Called our supplier and they brought out 3 more. All 3 were leaking! They say Dupont on them so we were assuming that they would be a good product.