The 2 1/2" Wilkins 350ADA is a double check detector assembly began production in 2004 and is still currently being produced. The body is constructed of epoxy coated ductile iron. Check assemblies are a plastic cam check design and springs are self contained. Spring tension does not need to be released to replace rubber discs. Retainer clips hold the checks in place. The 350ADA uses a single victaulic clamp style cover. The 350ADA uses grooved connections between the body and gate valves while the 350DA is flanged. Please be sure which model you have because some repair parts are different. Bypass device will be a 3/4" Wilkins 950XLD. In 2010, all bronze parts (test cocks, bulkhead fittings, ect.) were transitioned to lead free bronze to adhere to new codes. No special tools are required for servicing.