Description The Powermate check valve is part of the large line of Powermate genuine replacement parts. The check valve prevents air from going into the compressor head from the tank. Replace the compressor check valve with a new Powermate check valve if you have air leaking and cannot get your check valve to close off.1/2 in. NPT x 3/8 in. tube with 1/8 in. left bleederDurable valve closes when air has been drained from the compressor headCompressor check valve needs to be replaced when it does not close during compressor shut down and allows air to leak back into the compressor headA faulty compressor check valve will harm a compressor1/2 in. O.D. threads are 1/2-14 NPTF3/8 in. O.D. threads are 9/16-24 UNE-2A1/4 in. O.D. threads are 7/16-24 UN-2A1/4 in. port accepts aluminum, copper or nylon tubing