This pack is terrific, although I think a bit pricey. The CP-E4N is required for fast charging with the II series Speedlites; the older CP-E4 and similar units work with the new flashes, but deliver very slow recycle times. The CP-E4N cycles very quickly.

previously I had an off-brand external unit that was unreliable. This Canon unit is a powerhouse that supplies reliable non-stop flash power when needed.

Like all things Canon, this is a great piece of kit. Not cheap, but well made and a pleasure to own. I bought it for a run and gun shoot documenting a day in the life of a medical student and her professor.

I needed to make sure that my EX 600EX-RT Speedlite remained ready to fire while on the other side of the room when radio synced with the camera on the strobe and it works everytime with battery life to spare at the end of a long assignment.

So happy with this purchase. Really helps with recycle time on my Speedlite for event shooting. Worth every penny!

While overall performance of this battery pack is good, plastic tabs that hold batteries in place break off way too easily for a $200 product. Mine are breaking one by one after using it about 10 times.

Using the 600EXII-RT speed light as fill outdoors requires a lot of power - especially with a modifier (umbrella). Shooting at flash sync speed with a young family at the golden hour requires quick recycle rates to capture active children.

I was concerned about the problem with the pins on the cheaper model. No problems here.

Great when shooting on camera flash

On an outdoor shoot with my Canon 600 Ex shot through a 26 inch Octa I got much faster recycling which allowed me to focus on the shoot.