The unique wedge shaped park tools pp 12 hydraulic brake piston press slides into a hydraulic disc brake caliper to preset the piston when replacing pads aligning pads and performing other service procedures makes hydraulic disc brake maintenance and repair faster and easier park tools pp 12 hydraulic brake piston press features the unique shape and size of the pp 12 is perfect for compressing the hydraulic piston by pushing the brake pads apart to speed service and pad re