Performance MacHine Differential Bore 4-Piston Rr Caliper Chr H-D FXSTB/C FLSTF Features differential bore pistons that apply a different force at both the leading edge and the trailing edge of the pads to ensure superior breaking Dual-disc applications require the separate purchase of a left and right front caliper Available in chrome, polished, Contrast Cut and Black Ops finishes Contrast Cut finish starts with a polished caliper that has been black anodized, then recut to open the design Black Ops is a gloss black finish on top of a contrasting textured black finish for outstanding toughness and design