Wilwood Caliper-GM D154-R 2.50in Piston 1.04in DiscWilwood's newest race caliper, the D154 R starts with a forged aluminum Type III hard anodized body with stainless steel piston. With a choice of 2. 50 or 2. 00 pistons and covering rotors from . 81 to 1. 04 thickness up to 12. 19 diameter. Caliper fluid inlet port centered directly behind the piston eliminates any interference with slide pins. Lower deflection rate and higher volumetric efficiency than all the competitions heavier cast models, D154 R