Robinair 120v heater blanket speeds charging by maintaining a constant temperature at the tank, thus creating a positive pressure differential between the refrigerant source and the A/C system. Fits 30 and 50 pound refrigerant tanks. Secures with Heavy Duty Velcro strap. Thermostatically controlled to maintain 125° F (155° C). Thermal cut-off switch protects against overheating. 300 watts 2.6 amps.