Retrofitable 12V digital voltage measuring instrument. It can be built into most dashboards, the size of the hole to be cut is only 29mm, where it can be easily fixed with the instrument's retaining ring. Installation depth is 35mm. Overall diameter: 36.5 mm. Equipped with a switch, it can be fixedly connected to the power supply. This way, you don't even need the ignition key to check the battery charge status. If switched of it has no power consumption and does not load the battery.