The Hyperlight Journey 300 lumen solar powered flashlight-- it charges your cell phone, it's waterproof, and it floats. The flashlight only weighs 4 and 1/2 ounces. It runs 50 hours on a full charge. The journey 300 has a 2,500 milliamp lithium ion rechargeable cell. It holds a charge for seven years. The flashlight recharges with any light source or rapid charged with the USB port. Never buy a battery again.