RUBBERS FOR BOTH CHECKS AND THE RELIEF VALVE FOR THE RP4A/RPLF4A 1" MODEL.  THIS KIT REPLACES THE 4A00509.  THE ONLY DIFFERENCE IS INSTEAD OF ALL THE RUBBERS IN JUST ONE BAG THEY HAVE THREE DIFFERENT PACKAGES (TWO CHECK RUBBER KITS AND ONE RELIEF VALVE RUBBER KIT) IN ONE BAG.