# What do you mean by 'active switch' in the manual? The only active switch we're aware of is the Featherweight Magnetic Switch. These need three connections .. a ground, an input, and an output. Of the two switch screw terminals on Altus Metrum products, one is connected to the + side of the battery terminal and is the input to such a switch, the other connects to the output of the switch. Ground can be found on another screw terminal on TeleMega and EasyMega, there's an extra explicit hole you can solder a wire to on TeleMetrum, and all of our products have grounded mounting screw holes. For a typical, simple, mechanical switch .. you can ignore all this and just connect the two "switch" screw terminals.