for a fairly reasonable price, a good product, the things of Quantum are much more expensive. As a nice goodie you can also load his iPhone / iPad tuned. Tip: Do not forget With Canon flashes, the Custom Function 12 to turn in a flash. Which ensures that the power is drawn for flashes exclusively from the external battery source (if connected). An indication yet: One has won 4 regular batteries Canon flash have (restriction of Canon), the power pack is not enough!