This is a total rubber repair kit for "new style" the 10" Watts 909 Series reduced pressure zone (RPZ) backflow preventers. This kit includes all internal rubber parts for the first check, second check, and relief valve. The "old style" relief valve was produced from 1979-1989. The "new style" replaced the "old style" in 1989 and is still currently in production. An easy way to determine which relief valve you have is to measure the relief valve cover. The old style relief valve cover will measure about 12" in diameter. The newer style cover will measure about 9.75". This repair kit is for the new style 9.75" cover relief valve. No special tools are required for servicing. Genuine Watts replacement parts.