The Good: The Eton BoostTurbine 4000 charges your dead gadgets quickly and includes a hand crank for extra power. The Bad: The recessed power button is hard to press and the device is large. At $80, the BoostTurbine is expensive compared with its competition. The Bottom Line: The BoostTurbine 4000 is a reliable gadget charger for when you need extra power, but it's too big to slip into a pocket for everyday use. The Eton BoostTurbine 4000 is a unique portable charger. It's half everyday battery pack that can charge many modern smartphones, and half emergency power backup, thanks to its hand crank that lets you harness your elbow grease to power your dead iPhone. That makes it an ideal backup battery for powering your gadgets away from home, and helps you get power when there is no other power source, such as during a blackout, while you're camping, or if you've traveled to a remote area.\n\nMost emergency backup power sources I've come across, like this Ambient Weather model and this one from Eton, also include a radio and flashlight, which can be handy during an emergency or power outage. As such, I'd probably stick with one of those products in a natural disaster instead of the BoostTurbine.\n\nI would use the $79.99 BoostTurbine when after a long day my smartphone is dead and I need to call a cab. Even if it doesn't have any juice, I could spend a few minutes cranking it to build up enough energy in its battery to power up my gadgets.\n\nDesign\nThe BoostTurbine is roughly the size and weight of the type of power brick found on a power cable for a game console or laptop. It sports a smooth brushed-aluminum case with sharp edges on the bottom.\n\nOn the back is the plastic crank that snaps into the main body for storage. The crank has a firm hinge that moves smoothly and keeps the crank in place. That's a plus, because I've used crank chargers where the crank moved around a lot while I turned it, making it hard to get into a momentum and charge the battery.\n\n\n\nThe hand crank rotates both clockwise and counterclockwise, and while you turn it, the crank makes a loud whirring noise that's typical of other hand-crank gadgets.\n\nAlong the top of the BoostTurbine, there is a standard USB and a Micro-USB port, a power button, and LED indicator lights (more on those later). The device comes with one Micro-USB-to-USB cable, which you use to charge your gadgets. You can also charge the BoostTurbine itself by connecting the cable to your computer's USB port and plugging the Micro-USB end into the charger's corresponding port. \n\nEton calls the device pocket-size, but it's a bit clunky for that description. It's too large to fit in most guys' jeans pockets, so I can't see this being something you take with you everyday. It will easily slip into a purse or laptop bag, but at 9 ounces, you'll notice the extra weight.\n\nCharging the BoostTurbine\nYou can charge the BoostTurbine 4000 two ways, by plugging it into a power source, such as a computer or wall outlet adapter, with the included cable, or by using the hand crank. On separate occasions I used my computer's USB port and a typical USB-to-wall-outlet adapter from a smartphone charger to get the BoostTurbine to a full charge.\n\nIt's worth noting that you can use the cable to charge any gadget that has a Micro-USB port. To charge an Apple device, you'll need to use your own 30-pin or Lightning cable and plug the USB end into the port on the BoostTurbine.\n\nWhen you turn the hand crank, you're creating kinetic energy that is stored in the internal battery as reserved power. As soon as you connect your smartphone to the BoostTurbine, your phone will transfer that stored energy into its own battery. Eton says that 1 minute of cranking will give you 4 minutes of talk time. You need to rotate it about one or two revolutions per second to generate enough energy to charge the battery.