This is a rear caliper piston for a Jaguar E Type 1968 to 1974 and Jaguar XJ 1969 to 1977. Four are needed per car. The pistons are Plasma Nitrided which will give you the life of Stainless at half the price. The Nitriding becomes a part of the metal and will not flake off or seperate, you can't buy a harder caliper piston. 64325436 19-1207