Quick-Silver / ST series FNSLR/ST nickel plated forged billet calipers, with four Thermlock pistons, deliver championship proven performance with piston sizes to provide matched rear braking bias for use with the W6AR/ST or other larger piston front calipers. FNSL4R/ST calipers incorporate race technology into a radial mount body design with widespread adaptability. Including competition update options for all FNSL4R rear Big Brake kits. Thermlock pistons, high-temp seals, SRS bridge plates, and two-piece bleed screw assemblies are standard in all calipers. Four high-temp race only brake pad compounds in the 7416 pad type allow precise tuning of the brake response, friction requirements and temperature range