905491 (Febco) | 4 Inch | 850/860/870/880 Series DC And RP Complete Check Rubber KitThis Complete Rubber Repair Kit Includes The Parts Necessary to Repair or Replace Check Rubber Parts of a 4 Inch Double Check Valve Assembly, Double Check Detector Assembly, Reduces Pressure Zone Backflow Assembly Series 850 860 870 880. Kit Includes 2 Check Discs, 2 Cover O Rings, 2 Bearing Sockets, 2 Seat O Rings, Cover Plate O Ring, Sensing Line Cover Gasket, And Mounting Hardware. All Parts Are Genuine And Original to The Valve. Febco 905491