Wilwood 120-8373 CALIPER-PS 1-RHWilwood 120 8373 CALIPER PS 1 RH The PS 1 Caliper is compact, lightweight (. 93 pounds) and combines the strength of cast aluminum construction with a sleek low profile design. This caliper utilizes two stainless steel deep cup pistons to minimize heat transfer from the . 30 thick pad to the brake fluid while employing high temperature square piston seals to control piston retraction. Internal crossover brake fluid passages eliminate the use of