I'm looking into external battery packs for my SB910.

Anyone have any advise on selecting a battery pack for my speed lights? Do I really need the most expensive battery back when the batteries are the ones doing the work? I already own the best Eneloop rechargeable batteries.

No advise, I don't even have one... But it seems two factors. One, it is more than a box. The battery pack also provides its power converter that changes the 8x1.3 = 10 volts to about 325 volts to directly recharge the flash capacitor in a second or so. But two, the Nikon brand price does get your attention (on any item), and the other several models can do the same job for maybe 1/4 the price. It would tempt me. But I really have no issue with just the four Eneloops.

Thanks for the info, I did my research but I didn't find anybody talking about this. I don't cut corners when it comes to my equipment but I don't want to waste many on a grand. As of right now all my equipment is original Nikon or the best of it's class; like my pocket wizards, manfrotto tripods, light stands, etc.