ChemSaverdrip-free shutoff check valve opens / closes at 0,7 bar, with diaphragm made of chemical resistant EPDM. The nozzle pipe needs a 7 mm or 10 mm drilling. Max operating pressure 20 bar. An O-ring sealing and bolts are included. Can be mounted to 20 mm, 25 mm, 1/2", 3/4" or 1 " pipe or equivalent size tubing.