This is the Novak Smart-Stop Auto Detect Voltage Cut-Off Module. The Smart-Stop Auto-Detect Module is easy to install, and connects between the receiver and speed control. It uses a combination of throttle interruption and a visual cue from a remotely-mountable, ultra-bright blue LED. If the vehicle is run beyond the warning period, the module will bring the motor to a stop, while leaving full steering control. The Smart-Stop Auto-Detect Module 2S-4S also features an automatic set-up that requires no additional input, and a replaceable LED harness and receiver harness.