Avid Elixir Caliper Piston Kit Replacement Parts Sometimes the parts on your bike will wear out with regular use. Luckily, we have you covered with the replacement parts. The Avid Elixir Caliper Piston Kit comes with two 21mm Caliper Pistons and seals for your Avid Elixir hydraulic disc brakes. Features Manufacturer's part number: 11. 5015. 032. 000The kit includes: two 21mm caliper pistons and seals Designed for the Avid Elixir hydraulic disc brakes | Avid | Elixir Caliper Piston Kit For Avid | Elixir Brakes Only