Watts 709DCDA is a double check detector assembly. The 2 1/2"-10" sizes began production in 1979. The 2 1/2"-10" size bodies are cast iron with a fused epoxy coating. The 2 1/2"-3" size are available in either bronze or fused epoxy coated cast iron. Internal hardware parts are made of bronze and stainless steel. Check seats are replaceable on all sizes. Double check detector assembly. Production began in 1979. The assembly utilizes the 709 design on the main valve and the bypass unit. In 1991 the bypass was changed to the 007M1 model. In 1993 the bypass was changed to the model 007M2. In 1998 the bypass was changed to the 1/2" 007.