ISR 73-201 switch clamps. Fit all of the ISR master cylinders the switch clamps integrate switching and signalling functions into a unique and clean housing. ISR 21-012 front brake racing master cylinder. CNC machine from sold billet aluminum, infinitely adjustable leverage ratio, adjustable reach, modular construction allows fast repairs. ISR brakes from Sweden are extremely high quality, have a unique design, and deliver unbeatable performance.