This is the back-up battery with a charger that converts one minute of hand cranking into four minutes of emergency power for a connected cell phone. Ideal for placing an essential call or sending a text when power is not available, its fluid operation provides the same crank-to-power efficiency as dynamos used in larger emergency radios. Its integrated 2,000 mAH lithium-ion battery recharges fully in 2 1/2-hours from a USB connection to most computers or USB AC adapters using the included cable, providing ample energy to fully charge most smartphones (requires smartphone charging cable). An LED indicates the battery's charge level. The dynamo folds and stows into the charger's lightweight yet durable aluminum body for easy portability in a shirtpocket, glove compartment, or bag. 5" L x 2 1/4" W x 1" D. (7 oz.)