It uses an infrared sensor to recognise when your appliances have gone into standby mode and turns them off to save energy.

These sensors include: sonic, which work like radar; optical, which uses an infrared sensor; and bumper, physical contact sensor.

It may either operate with a button, or more recently, automatically using an infrared sensor.

For example, the inspiration for the infrared sensor came from the thermosensitive pit organ of rattlesnake.

An optional infrared sensor was available as well.