Firestone Air-Rite Air Command Compressor Check Valve 1/8NPT - 1 Pack (WR17603468)This compressor check valve ensures that air does not backflow from the tank into the compressor head. Air tanks cannot maintain proper pressure unless a check valve is installed. Prevents backflow of air from tank into compressor head Ensures that air tank maintains proper pressure. Includes (1) 1 8 in. NPT male fitting and 1 female fitting. Made in USA. 2 Year limited warranty.