A relay is an electrically operated switch that allows you to turn on or off a circuit using voltage and/or current much higher than the Arduino could handle. There is no connection between the low voltage circuit operated by Arduino and the high power circuit. The relay protects each circuit from each other. This module features an 250v 10A mounted on a 2 module TinkerKit board, one standard TinkerKit 3pin connector, one transistor, a green LED that signals that the module is correctly powered and an yellow LED that indicates when the relay is active.
This module is an ACTUATOR. The connector is an INPUT which must be connected to one of the OUTPUT connectors on the TinkerKit Shield.