The 3" Watts 757DCDA Double Check Detector Assembly began production in 2000 under the Hunter name. In 2002, Watts bought the rights to the device and began production as the 757DCDA name. The body is made of stainless steel and uses a single sliding cover. The #2 test cock must be removed in order to slide the access cover. The check assemblies are a plastic cam check design using a self contained torsion spring. The first two years, the bypass device was a 3/4" Flomatic DCVE. After 2002, the bypass was typically a 3/4" Watts 007M3. All 757 devices are lead free. No special tools are required for servicing.