The Bogen Model PRS40C power supply provides unregulated 12V DC at 300 mA from a 120V DC, 60 Hz source, and its maximum power consumption is 8 watts. The sleeve of the mini plug (and the lead with the white tracer) is positive. The unit's dimensions are 2" W x 2-3/8" H x 1-5/8" D and the power supply is UL listed.