For Rotating Pistons Back into the Caliper to Provide Clearance for New Pads. Includes 5 adapters (available individually) for use in both 2 and 4-wheel rear disc brake assemblies of most domestic and import cars. Tool may be used "on" or "off" the car. A real time saver that makes this tough job easy. Helps prevent damage to the prevent damage to the piston and boot. NOTE; some pistons turn clockwise while others turn counter-clockwise; consult your shop manual for the car you are servicing. For the counter-clockwise rotation the 1' Hex Nut must be turned at a faster rate of rotation in order to keep the adapter engaged with the piston. No longer includes retaining ring. Can be used left handed but does not work as well.