The superior strength of this innovative new caliper is combined with proven performance features from other Wilwood designs. Each caliper is equipped with Wilwood's replaceable SRS stainless steel bridge plates. SRS plates eliminate the bridge wear caused by pad gouging and extend the service life of the caliper body. The spring-loading action of the SRS plates also eliminates pad rattle and dampens the vibration harmonics that contribute to squeal under braking. Other standard Wilwood features include high-temperature, square faced piston seals which provide a full contact sealing surface and maintain their resilience through long service cycles for effective and controlled piston retraction. Fluid transfer tubes are dampened and recess mounted to eliminate fatigue from vibration while adding protection against damage from track or road born debris. Center bridge bolts provide positive pad retention with easy access for service without caliper removal. Two-piece bleed screw assemblies provide long, reliable service life and are easily replaced if necessary.

Forged Billet Superlite differential piston bore calipers are a direct replacement for all Wilwood Superlite and similar competitive brand calipers with 3.50" centered mounting tabs. Calipers are available in the popular 1.88/1.75" piston sizes for .81", and 1.25" rotor widths. FSL4/ST calipers use the same 7420 type bridge bolt brake pad used in all Superlite 6 piston calipers. The full range of PolyMatrix and Wilwood BP series pad compounds are available to match brake response and heat range to any application.