This is a first cam check assembly for the 6" Ames 2000SE/3000SE double check valve assemblies. The "SE" devices are based off the "SS" series backflow assemblies. The "SE" stands for "Special Edition" and uses smaller parts than the "SS" so be sure which model you have. Simply unthread your old cam check and thread in this brand new complete cam check assembly. Includes a new cam check O-ring. Genuine Ames repair part. No special tools are required for servicing but a handy cam check tool is available to assist in removal and replacement of the cam check assemblies.