One new 1/2" compression x 1/2" male NPT in tank compressed air check valve. This style of check valve is usually screwed directly into the air tank, then the main line coming off the compressor pump is connected to it. This valve prevents backflow or tank pressure from getting back into the air compressor pump once the compressor has been shut off. This valve has a 1/8" female NPT port in the side which usually goes to an unloader valve on your pressure switch or compressor pump. If your application does not use an unloader line, this port can just be plugged.

Specifications:

Total Length: 2-3/4"

Tank Threads: 1/2" Male NPT (measure about 3/4" in diameter)

Compressor Line Input Threads: 1/2" Compression (measure about 11/16" in diameter)

Unloader Line Input: 1/8" Female NPT (measures about 10/32" in diameter)

Installation Wrench Size: 7/8"