This hand pressure tester is used for checking the pressure in the can, not through the valve. It's great for BOV or piston cans or cans with metered dose valves. It attaches to the can with the clamps supplied. It pierces the can with a self tapping valve. It has a toggle valve for pre-pressurizing accuracy.*Comes with brass toggle valve and test report, traceable to N.I.S.T. Rugged Plano lockable gun security, foam padded carry case, Also made in USA.