Rear Disc Brake Piston Tool Removes and installs disk brake pistons. Rotates piston back into caliper cylinder. Use on most imports, Ford, Chrysler and GM cars with four wheel disk brakes. Use with 3/8″ drive ratchet wrench and extension bar. Suitable for vehicles with discs all round. Retracts parking brake piston prior to installation of new pads. Five possible pin configurations. Fits US and European applications.