The power mirrors found in today's modern cars are controlled by both the user's input and the computer within the automobile. The user toggles the button (usually located on the driver's side door), which then sends a signal to the central computer. The computer then, depending on the desired direction of motion for the mirrors, tells various circuits to either stay open or closed. With a source of power now running through the circuits, the mirrors are able to move up, down, or be angled in a position for optimal vision for the driver. This accessory can be found on the same circuits and power source as the power windows of a typical car.