Description: Pair Hydraulic Disc Brake Caliper Pistons set for mountain road bike brake repairing, fixing Made of high quality material provides great heat resistance effect which can resistant 400 degrees Celsius High performance, very stable, unbreakable and no tearing even after extreme and continuous braking Fan shaped heat sink design increases air shuttle to promote heat dissipation Compatible with FOR Shimano ZEE BRAKE M640 M810 M820 M7120 M8120 M9120 Disc Brakes Specification: Thickness: 8.8mm L Diameter: 17.2mm S Diameter: 15.1mm The outer diameter of the large seal ring is about 21.4mm, and the outer diameter of the small piston seal ring is about 19mm, with a thickness of 2mm Five small sealing rings: wire diameter 0.8, outer diameter 8, inner diameter 6.6, Wire diameter 0.9 outer diameter 8.5 inner diameter 6.7 Wire diameter 1.1 outer diameter 9 inner diameter 7 Wire diameter 1.4 outer diameter 9 inner diameter 6.2 Wire diameter 1.4 outer diameter 10 inner diameter 7.2 The elastic size of the sealing ring is the approximate size, Weight: large piston 2.1g, small piston 1.6g Package Includes: As shown in the option diagram