We use this module in all our RTR controllers. It has two 230V solid state relays. These relays are most often used used to switch a KRESS milling motor(Tool) and a coolant pump(Flood). The module interfaces with USBCNC CPU V4 or V5, via a ribbon cable. On the PCB there are 2 jumpers allowing you to choose which signal from USBCNC controls the relays. Options are for left contact Tool or Mist right contact Flood or AUX. The relays we used are 15 amps, so in theory could switch 3,5KW, but then relay would need to be actively cooled, we recommend to switch a maximum of 1,5KW. That is not a problem even without active cooling, and its more than enough for a KRESS milling motor or a Coolant Pump.