2 Piston - 3.75" Lug Mount DynaPro Single Caliper, Long Piston (Polished) WB120-2 Piston 3. 75" Lug Mount DynaPro Single Caliper, Long Piston (Polished)1. 75" 1. 75 Bore Size, 0. 19" Disc Width, 6812 Pad Plate WB120 9689 120 9689 Comes in two bore sizes, 1. 75" or 1. 38" and two mounting options, 3. 75" or 3. 25" Weights starting at only 2. 30 pounds Four corner bleed screws allow the caliper to be mounted in any front, rear, right, or left position Internal fluid passage eliminates external crossover tubes One piece stainless