The 3" Ames Maxim series M-200 Double Check Valve Assembly began production in 2000 under the Hunter name. In 2002, Ames bought the rights off of Hunter and is still manufacturing the devices. The body is constructed of stainless steel. Similar to the Colt Series, the Maxim features larger internal parts to increase flow rates. It is offered in a number of configurations with many valve options. To access the check assemblies there is a stainless steel sleeve that will slide open. You must unthread the #3 test cock then slide the cover. The Maxim uses two self contained cam checks that use a tri-link check mechanism. Numerous repair parts are available for the Maxim series devices, including rubber parts and complete parts.There are no special tools required for service.