 Commonly, such radios are designed to use minimal battery power, and a common feature (especially on units sold in less-developed countries where electrical supplies may be unreliable or nonexistent) is a hand-cranked electrical generator along with a rechargeable battery to store the generated energy (the device is sometimes known as a clockwork radio).A few, such as the Blackout Buddy from Eton Corporation, and the Adventurer from Ambient Weather are designed to recharge from wall current.Some emergency radios can also be powered by an attached solar panel.