The Wilwood Forged Narrow Superlite 4R (FNSL4R) is our newest version for the venerable Superlite caliper series. Radial mounting simplifies adaptation and provides two planes of adjustment for accurate alignment over the disc. These calipers integrate in Big Brake in style to generate big stopping power in extreme environments over a broad range of vehicle applications. The key to the superior performance of the FNSL4R comes from the extremely durable and efficient body design. Starting at 4.9 pounds it is the product of computer generated solid modeling and FEA stress analysis technology. The most noteworthy feature of this new caliper design is the forging. Each body is stress-flow forged from premium grade aluminum alloy billets. Stress-flow forging re-aligns the metal's internal grain structure to flow within the contour of the caliper body. This process eliminates the stresses and interruptions to the internal grain structure that occur when machining a straight block billet. Simply stated, there is no better way to build a stronger aluminum caliper body. Available in diiferent piston bore sizes, provides braking as either a front or rear caliper. The standard FNSL4R calipers feature one-piece stainless steel pistons. Stainless is used for its slow heat transfer properties and high resistance to corrosion. Calipers can be upgraded with Wilwood's exclusive Thermlock pistons. This multi-part piston design creates a highly efficient thermal barrier to further reduce heat transfer from the pads to caliper body, seals, and fluid. Cooler temperatures translate to longer service life and less chance for heat induced pedal fade. In addition, each FNSL4R is equipped with SRS bridge plates. SRS plates eliminate all bridge wear caused by pad gouging and extend the service life of the caliper. The spring-loaded action of the SRS plates also eliminates pad rattle and dampens the harmonic vibrations that contribute to pad squeal. Two piece bleed screws on each end and internal fluid crossovers prevent damage from track debris and other potential damage sources. High temperature, square faced bore seals provide the largest possible sealing area and controlled piston retraction on release. The full range of Wilwood pad compounds is available to match the brake response and heat range of any competition or sports driving application.