You won't think there are some special for the surface of the door handle, but if it can control the your gas & power supply switch, you will be completely Surprised.
Through the door knob, you can see switch state about your room lights, natural gas, tap and household electrical appliances, and then you just casually open door switch, and press the handle at the same time, all the energy equipments can be shut down.
Written by Dora Men