To replace all of them you will need to order a quantity of 3.

Must order quantity of 4 for complete set. 

Air compressor cylinder ring and o-ring kit. Includes compression ring, head o-ring, and valve plate o-ring.  This tends to be a high-wear part, especially if you are in a high-particulate environment. Pro Tip: Order the cylinder when buying this...

Compression nut and sleeve for 3/8" OD tubes.

Old Part Numbers: Z-AC-0032, AC-0032Valve plate comes with preinstalled valves and o-rings. Poor performance or air leaks out of the intake filter while the unit is running? This is probably the problem.

Old Part Numbers: 5130038-00, 5130024-001/4" OD brass compression nut and sleeve for bleeder (unloader) tube for air compressors.