Easily replace brake pads on most four wheel disc brake cars. Makes clearance for new, thicker brake pads by rotating the brake piston back into the caliper until the piston is bottomed. Rotating the piston is required on most disc brake calipers which are also used as emergency brakes. 86100B, comes with 6 different sizes of adapters. Adapters #1, 2 & 3 cover a wide range of cars while #’s 4, 5 & 6 have been developed for the unique GM style brake piston.