In this new generation bicycle light system, no battery is needed, no
friction on any parts of the bicycle. The lights flash regardless speed
of the bicycle and weather conditions (unlike normal dynamos!). Very
bright.

It can be used as a stand-alone light system (as a normal dynamo) on
your bike, or used as a back-up for your existed battery-powered lights

All details and buy on-line: http://www.freelights.co.uk