United Safety's Vehicle Safety lock provides security for your emergency vehicle. The system requires a code to release the park brake (or to shift out of park for a non-air brake vehicle), and then automatically re-engages the security when the driver exits the vehicle, with no user interaction required. The system provides an additional layer of safety by monitoring the park brake, driver seat, and driver door, if the system detects that the driver has exited the vehicle without engaging the park brake the system automatically engages the brake preventing a potential vehicle rollaway.