JEGS Universal Rubber Master Cylinder Boot is designed to replace a worn out or torn boot, or to be added to a master cylinder that does not include one to guard against the elements that may enter into the piston area. Fits a 1-3/8" O.D. master cylinder register. Measures 1-3/8" I.D. x 2" O.A.L. and Accommodates 1/4" to 3/8" diameter pedal rods.