Drilled sprotors are for custom Harley Davidson motorcycles (HD), custom choppers, bobbers and most custom motorcycles. Everything is on the left side of the motorcycle rear wheel, to leave the right side completely clean: this is a must for a true old school chopper. Sprocket-rotor brake combo kit includes a 51 teeth sprocket which works also as a brake rotor, two piston rear brake caliper with built-in caliper bracket, brake pads and necessary hardware for your custom chopper. Caliper is made out of billet aluminum and is available polished or black anodized. Sprocket-rotor is made out of stainless steel. These chopper brakes are available for either left side or right side drives and work on all hubs without locating flange or hubs with pre-1999 locating flange. Drilled sprotors perfectly match our front Drilled Rotors, Four Piston Super Smooth Calipers, Two Piston Super Smooth Front Calipers for Springers and Four Piston Super Smooth Front Calipers for Springers.