Keeps Bleeder Screws Free From Dirt And Moisture Keeps Dirt And Build-up From Forming On Grease Zerks Keeper Leash To Keep Cap From Being Lost During Service (Keeper Leash must be cut off to use with standard Grease Zerks) Inner Rib To Keep Cap Securely Fastened Soft Rubber For Perfect Fit Rubber caps keep dirt and moisture out of brake caliper bleeder screw fittings and Grease Zerks. Includes a Keeper Leash to prevent the loss of cap during service. Fits all common size bleeders screws and zerks. Has inner rib to help secure cap and keep it in place.