ZJEGO Dynamo Bicycle USB Generator Charger Kit, Portable and Waterproof - No Tools Required (Green)

Nice for the price. In built battery holds enough charge to power my Garmin edge to over 50% from dead flat.used this in all weather's for the last 3months and it has not flinched from working. When testing I found that under 10 mph it will charge battery pack a but a garmin will power down due to the low current, I normally charge up the units inbuilt battery ( about 2% per mile for my garmin edge). Worth the pounds.

If you keep your speed up this seems to work well charging an Iphone 4s but even if you don't if its internal battery is charged that will also charge your phone. It come with all the brackets and screws needed the only down side is it looks and feels a bit cheap only time will tell.