This is a 4-channel solid state relay (SSR) for AC power that can be controlled directly via a microcontroller. This device has a 2A resettable fuse to protect against overload conditions. Microcontroller inputs are isolated with an input transistor and opto-isolation that activates the switch on a LOW input signal with almost 0 current from your micro controller! SSRs are great because they do not have inductive switching noise from a mechanical switch and do not wear out.