The federal government is stepping in to end the use of an aftermarket product designed to let Tesla owners skirt a safety feature from the electric automaker’s semi-autonomous Autopilot system. The U.S. Department of Transportation’s National Highway Traffic Safety Administration issued a cease and desist letter Tuesday to a California company known as Dolder, Falco and Reese Partners LLC that is selling the Autopilot Buddy product. The Autopilot Buddy product, which is marketed with the catchy slogan “Tesla Autopilot nag reduction device,” is a magnetic piece of plastic that disables the feature in Tesla vehicles that monitors the driver’s hands on the steering wheel and warns the driver when hands are not detected.