This relief valve repair kit fits the old style 8 - 10" Watts 909 Series backflow preventers. 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 old style 12" cover relief valve. Does NOT include parts for the bypass assembly. No special tools are required for servicing. Genuine Watts replacement parts.