[Fit for Disc Brake] The brake caliper press tool is equipped with two groups of push boards: 7.01x2.36 inches and 4.53x2.17 inches, Suitable for most single and twin pistons floating calipers, twin and quad pistons fixed calipers or some sextuplet pistons fixed calipers (Just make sure the piston calipers space can accommodate the spreader)[Working Principle]The spreader can spreading to push the boards or retracting when finished it. (Ajust by the switch). In expanded mode, the centrally located ratchet screw creates uniform thrust to the push boards that can quickly push several pistons in the caliper at the same time. Effectively save energy and greatly improve efficiency.[How to use]Make the push boards both sides Centralized Alignment the pistons, let both sides of the push boards be forced at the same time (press both sides to assist in starting until push boards press the pistons), swing the handle until the push boards press the pistons to the suitable position, last, ajust the switch, retract the boards to remove the spreader.[Size Reference]Two groups of push boards size: 7.01x2.36 inches and 4.53x2.17 inches; Telescopic range: fully retracted: 1.88", fully expanded: 3.03".