Mastercool 85510 R134a Can Tap Valve-Screw-On Model Screw-on design for R-134a can taps Gasket assures leak proof operation M14-F x M10-FL-M. Gasket assures leak proof operation. Built-in safety check. Exclusive full grip valve knob. Screw-on design for R-134a can taps Gasket assures leak proof operation Built in safety check valve