I saw a similar device in a friends new build 3-4 years ago. It used the energy from you pressing the switch to transmit to the fitting.
My favourite history. Pat Grace's Famous Fried Chicken: https://open.spotify.com/episode/0uFbJFPRxd7Or4EiJ1V0jy
I saw a similar device in a friends new build 3-4 years ago. It used the energy from you pressing the switch to transmit to the fitting.