This second check repair kit provides all the parts necessary to repair or replace the second check on a 6 inch double check valve assembly backflow preventer, model 774 and double check detector assembly backflow preventer, model 774DCDA. This kit consists of a complete number one cam check with a check O-ring. WATTS®, 0888823, Second Check Repair Kit, Series: 774DCDA, For Use With: Model 774/774DCDA 6 in Double Check Detector Assembly, Import