I'm sure it would take alot of cranking to charge a phone fully but as it says it's just for emergency, for a one off call.
Cheap (£1.87 delivered approx).
Only plastic so it wont take much to break I expect.
Site Info :
- Built-in LED lights up and power is being generated and your phone is being charged
- Compact, stow-away handle design makes the unit easily portable
- Comes with wrist strap for easy carrying (18cm-length)