This is a self-contained Tail Light/Beacon Combination unit that requires no external power supply or modification for installation. It draws less than .2 amps so you will save 2 amps in the circuit and gain a beacon. It also, fits in the same footprint as your current Grimes, Whelen, or other standard incandescent tail light unit. No RFI, runs cooler and longer. Available in 12V & 24V. NON-PMA