The medium and heavy duty commercial vehicle industry continues to evolve globally. In India, market dynamics for commercial vehicle manufacturers are changing quickly. New market entrants as well as a focus on safety, total cost of ownership, and new regulations are forcing the rapid adoption of technologies that have proven important in other global markets. The engine brake is one of these technologies.The engine brake has become a standard in many worldwide markets because of its ability to provide highly safe, efficient and cost effective supplemental retarding in downhill conditions without time or temperature limitations. It addresses the common concern of exceeding the thermal limitations of a loaded vehicle's foundation brakes on a downhill grade, which may significantly reduce the stopping capability of the vehicle and put the driver, truck, load, and other people on the road in significant risk.In terms of India braking regulations, the country's recent adoption of UN ECE Regulation 13 (India regulation 11852) for supplemental retarding is driving the development and adoption of engine brakes. This regulation is common around the world and requires operators to maintain a specific downhill speed under certain grade and load conditions without using the foundation brakes. The engine brake is the most commonly accepted method for complying with this regulation.The engine brake also provides significant value to the end user by lowering the total cost of ownership of the truck. The use of an engine brake will significantly reduce the wear on the foundation brakes thereby increasing the interval between service events. The engine brake itself provides a payback period on its investment of approximately 1 year.This paper will discuss the basic operating principals of the engine brake with a focus on items that are critical to adoption in the India market.