The variable vane turbochargers used in diesels today to reduce turbo lag, emissions and increase power can also be used to slow you down. BD utilizes this technology by electronically closing off the turbine vanes which can create up to 130 retarding horsepower. This braking force will help to maintain your speeds on descents and curves, giving you better control of your truck and load. Works with your cruise control to automatically accelerate and decelerate to maintain vehicle speed. Easily and simply installs by plugging into existing factory connectors and by mounting the switch on your dash.