The starter relay (or solenoid) is responsible for passing power to the starter motor.
The relay remains internally disconnected until 12v DC voltage is applied to the two small wires.
Important note! Our solenoid comes with the standard GY6 2-pin connector. Some of the early manufacturers of some models cut a corner there and hardwired the solenoid directly to the harness. This was a bad idea. Known models include Yerf Dog, Tomberlin, Baja Dune. The verification status is rightfully "Direct Fit", as no matter what you do, you'll have to splice in a solenoid.
Almost all other models have the correct connector.