The 6" Watts 993RPDA Reduced Pressure Detector Assembly (RPDA) was produced from 1998-1999. The body was constructed of fused epoxy coated cast iron. Designed for verticle installations. Check springs are contained when the cover is removed. Check seats are replacable. The relief valve assembly is constructed of bronze and threaded onto the body. An external sensing line is used. The bypass device shall be a 3/4" Watts 009M2 or 3/4" Watts 009M3. No special tools are required for servicing.