Here is my "radio delete" volt meter. It is not switched so it is on all the time. I use it to see when it is time to charge my battery. It was advertised as a marine application. USB, volt meter and cig lighter. I think I bought it on Amazon. Car is a 73. I slid the face plate in the channels with the glove box open. Tapped aluminum backing pieces. Has 3 inline fuses.