10" Ames Maxim 200N Series Double Check Valve Assembly. The Maxim 200 is similar to the Colt 200 but uses larger parts to obtain a higher maximum flow rate. Constructed of stainless steel, the device features OS&Y (Outside Stem & Yoke) Gate Valves with flanged ends. This device is an "N Pattern" configuration. 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 200 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.