BD Diesel Exhaust Brake - Universal 3.5in c/w Air CompressorIt has been almost 30 years since we started shipping our first exhaust brakes. With that many hill and mountain roads experienced, we used the knowledge gained to continue to deliver the best designed exhaust brake for your application. Incorporating BD's exclusive Variable Orifice Technology, BD's solid, offset butterfly, spring loaded cylinder and pressure regulation provides up to 150 retarding horsepower throughout the engine's RPM range not just