ENERGIZER 120W Cup Inverter is perfect for most needs as long as you are aware of the power output limitations. Remember even-though it has one 120V AC socket does not mean that you can plug anything you want and expect it to run. In my tests I found out that hardware engineers at ENERGIZER has given considerable amount of thoughts with 'safety & protection' in mind when designing this product. In most cases 'over-estimating' the load momentarily causing  the DC & AC outputs to cut-off while in operation. Having said, It does work perfectly when you keep the load on the device well below the limits of 120 watts.Also, as there are no physical ON/OFF switch for this CUP inverter, embedded smart electronics in the device constantly monitors the load & will change the bi-color status LED from Blue to RED indicating overload. I found that the USB ports current draw & the 120 watt inverter share the same 'overload' logic. This can be a problem in some situations wherein the 120v A/C load may draw little bit above the rated limit thereby momentarily shutting off the USB ports. Once the overloading device is removed the unit will automatically start working. While this design keeps the user & device safe during operation it can add some inconvenience inadvertently when the user without knowledge adds a device which overloads the device.PROS[+] Silent Operation[+] Good safety protection[+] Small design with 4 USB ports[+] Includes Battery Clips[+] Smart power draw (Draws power only when load is detected)CONS[-] Bright Blue Light is a distraction while driving.[-] The shape & design of the cup inverter can be problem in some cars as it tends to fall out.[-] The overload circuit is common for both USB and 120v inverter cutting off USB output at times.[-] If you plug-in all four USB ports for charging it would take long time to charge the devices as they are shared.Side-note:Not having a Physical ON/OFF switch is not a deal breaker for me. But worth mentioning as it can be a problem in some cars wherein the cigarette lighter port does not power off when key is removed as it might drain the car battery if left unattended with a large load. Without any load however the device draws negligible current &lt;20mA and can be left connected to the car's cigarette lighter port.I really like this product apart from the limited power of 120 watts. Perfect for most needs and the price is just right.Thanks for reading my review. Happy Shopping!