Powered and Controlled from the USB bus.
Relays - 4 with integrated snubbing of the normally open terminals
Power - Powered from standard USB bus
Control interface - USB with a mini B connector
Relay current - Up to 16Amp @24vdc or 250vac
Connections - Screw Terminals for N/O N/C and Common contacts.
Integrated snubbers have be added to the module between the common and normally open poles. When inductive loads are to be used the snubbers suppress the switching spikes and relay arc associated with such loads.
We have a simple guide here
Linux GCC - A command line tool that will set the relay states according to input from the user