All the switches have 3 terminals, the bronze colour connects the internal light
Panel mount diameter: 20mm
Overall dimensions: 30 x 23mm (Height x Diameter)
Switch Rating: 20A 12V DC
Light Rating: 5-16V DC

How to connect?
Check the second picture for diagram
Basically the "silver" pins are the contactor (positive (+) wire) and the brass pin goes to minus (-) to supply the internal light with power, when contactor is switched

KCD1 Round Rocker switch