The smartphone case with a built-in hand crank
A smartphone case which is capable of charging your phone using a built-in hand crank has gone on sale.
Five minutes of cranking can provide about 20 minutes of talk time or an hour's worth of smartphone usage.
Other hand cranks are available, but this is the first time one has formed part of a phone case.
BBC Click's Marc Cieslak reports
15 Jan 2016