The Lumedyne HV Cyclers On-Camera Power Solutions fits Canon brand flashes that have an HV connector ranging from the 430EZ (Not 430EX) all the way to the 580 series and the current 600EX-RT. It also fits many other popular brands with similar HV connectors like Nissin, Bolt and Genesis and others, although some brands may mount at a different angle to the flash and be better suited for off camera use.
The Lumedyne “X” is able to double (or more) the flashes per charge of the flash’s internal AA’s while also cutting the recycle time of all settings about in half. It does this through the High Voltage port on your flash to make the recycle time faster and extend your AA battery life by lowering the HV workload, not doing anything for the six volt demands like the power zoom or display.
The better powered your AA's are, the better your overall performance. However, the X helps with the recycling process to make it easier for the AA's and provide a faster recycling time at any power setting. The X will help even more as the AA batteries get less of a full charge, sometimes cutting the recycle time to less than a third of that of tired AA batteries. This allows you to use your AA's to the fullest.
The built in Lithium-Ion battery is USB rechargeable and each X includes a dual car charger and a dual international AC charger along with a couple of USB Micro cables. It charges fully in three hours and each charge is well balanced with the full run-time of a set of AA's. It has safety circuits to protect the battery from damage and includes Two Years of Performance Warranty for the battery and the rest of the product.
No other HV Pack is available which can plug directly into the flash's HV connecter and assist the flash to run faster and longer. It is still advised that you do not continuously flash your flash at the full speed that the X will help you to recycle so that you do not over heat your flash. If you shoot at the same rate that you normally do, while the the X is helping the recycling process, the AA's will produce less heat inside the flash. The fact that the X is not quite as fast as the larger and heavier HV Packs, which all require extra cables to plug in, is often considered safer for the flashes, but still use reasonable judgement and don't shoot it too fast for too many flashes in a row. However, you can enjoy faster performance for every flash opportunity by adding just this very small, 2.3oz HV Pack directly to your flash.