Narrow Mount DynaPro (NDP) forged billet calipers represent the next generation of calipers available as an upgrade or direct replacement for the popular Narrow Mount Dynalite model series with 3. 50" mounting. NDP calipers combine superior strength with several new performance enhancements to make these the best "Dyna" series calipers ever built. The strength of the new DynaPro is a combination of process and design. NDP calipers are stress-flow forged from premium grade billet. Stress-flow forging realigns the grain structure of the metal within the contour of the body design. This process produces a part with superior strength over parts simply machined from straight grained blocks of billet. The FEA generated body design incorporates a highly fortified radial transition that eliminates steps and shoulders between the piston housings and the bridges. Incorporating a radius in this critical area substantially increases resistance to deflection and caliper body separation under load. For additional strength, all NDP calipers are fitted with center bridge bolts to provide additional resistance against separation over the center of the pads. Structural deflection and volume displacement testing have proven the efficiency of this innovative design. Reductions in overall deflection, and the subsequent decreases in fluid volume displacement, translate to increased clamping efficiency with less pedal travel. The bottom line is a firm, responsive pedal with outstanding stopping power. The DynaPro is loaded with other enhancements for performance and wider application. The calipers feature Quick-E-Clip pad retainers that support a 7816 type brake pad from the top. Not only does it allow for fast pad service without caliper removal, the bottom pad supports common to the earlier NDL models have been removed to create a slimmer profile with more bottom side clearance and easier mounting in tight clearance applications. Heavy wall stainless steel pistons are used to resist corrosion and slow the heat transfer from the pads. The heavy wall sectional thickness also provides additional strength against backside deflection to provide a firm pedal feel with efficient clamping at all pressures. Each NDP is also fitted with replaceable stainless steel SRS bridge plates. SRS plates eliminate the bridge wear caused by pad gouging to 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 during engagement. The package is completed with internal fluid passages and four corner bleed screws that simplify bleeding regardless of the mounting location.Pit Stop USA offers Wilwood Narrow Mount DynaPro (NDP) Forged Billet Caliper - Side Inlet - 3.50" Mount - 1.75" Pistons - .38" Rotor Width 120-9734-SI at low everyday prices. Be sure to check out all of our products from Wilwood Engineering including Wilwood Engineering Dynapro Narrow Mount and Wilwood Engineering Brake Calipers.