Old Part Numbers: SSF-3158-1This is the screw that holds down the piston cover, on the top of the piston.

Air compressor check valve. 3/8" Comp x 1/2" MPT with 1/8" FPT side port.  The check valve is a one-way valve that prevents air from back-feeding from the air tank. If your unit has a hard time restarting when trying to cycle or your pressure switch...

Old Part Numbers: GA016300AV, GA016310AV, GA016303AV, GA016308AV, GA016313AVPressure Gauge. 0-300 PSI, 1/8" NPT, Right-mount, 1.625" face.

Order this if ordering valve plate or a new head.