THIS POWER SUPPLY IS SPECIALLY FOR BMW OPS PROGRAMMING. USUALLY FOR PROFESSIONAL PROGRAMMING FOR NEW BMWs, IT IS NO NEED TO RUN A CAR TO SUPPLY FOR PERMANENT AND STABLE VOLTAGE.ADJUST 12.8 VOLT--13.5 VOLT IS POSSIBLE.ADITIONAL POWER SUPPLY TO MAKE SURE IT'S SAFETY. IT CAN ADJUST THE AC AND DC.IT'S VERY STRONG AND STABILIZATION.