12 volts electronic transformer the power output is pefect giving the most natural light yet. It runs the lights very smoothly and consistently. However as with all resistance transformers it will not output it voltage until there is enough load. a minium load of 20 lamps is reqiured.This compact unit is only Dimensions: 120mm x 30mm x 21cm and can be hidden under the baseboard out of the way. The Tech bit Input 230v-50hz output 11.9 v~ AC elf (20-60VA) supply current 0.26A thermal protection & auto reset please note this unit is not suitable for LED's If you need any futher advise on this please feel free to contact me.