To install the seals on the pistons, place a little bit of the appropriate brake fluid on the piston to lubricate the seal. You simply have to slide the seal into the slot provided. There is a raised surface inside the groovemake sure that the seal passes that raised surface and seats securely on the bottom of the groove. If you have to use a screwdriver to maneuver the seal in the groove, be careful not to scratch off any of the anodizing on the piston. This is what keeps the piston from oxidizing and seizing in the bore.