Solid aluminum alloy housing, it is more durable than other plastic cases. A slight drop or impact will not affect the internal parts More comfort, less heat. The cooling fan is normally started at 1/3 of the rated power of the inverter. After rotating, the efficiency will not decrease, but increase. With 2 Smart USB charging port, can auto detect your devices and deliver best matched charging current to get fast charging speed. BLB-600W Pure sine wave powerinverter has 20% margin (720W transformer) design, this keeps the inverter fromworking at peaks, increasing the inverter operating life by more than 30%. If the load is 150W-600W, only connect battery clip directly to the 12V car battery. A power supply and battery serve as backup power into the inverter.To use it at much 150 above to 600 watts it needs to be connected to the car battery. If the load is under 150W , The cigarette plug way can be used. This device is great as it plugs in where the cigarette lighter plug use to be handy, you cannot get 600 watts from 12volt car cigarette lighter, needs alligator clips for battery.