[0.165 lb] Great value compared to the price of the Canon model. I have had not issue with the connection not working as stated in some of the other reviews. The product works as expected and is great at reducing the cycle time of my flash.

[0.165 lb] I am very happy with this product, and the price is fantastic.

[0.165 lb] This is exactly what I needed and it fit the bill perfectly and at a great price.

[0.165 lb] I've been frustrated with my 580ex II's for a while. If I was using the flashes at full power and I didn't wait a full 5-7 seconds between shots, the subsequent shots would be underexposed. I bought 2 of these battery packs (1 for each 580) and had a chance to test them this weekend. I was very pleased with the results. I fired the flashes very quickly (2 seconds or so), and every shot was exposed the same. The only improvement I would suggest is the ability to unplug the cord from the battery pack. I use PocketWizards on my 580's and they require the AC7 shield to function properly. Here's the annoying part, I have to remove the flash from the AC7 to plug/unplug the battery pack. Let me be clear, the inconvenience is NOT at all Bolt's fault. Other than that, I love these.

[0.165 lb] While probably not durable enough for daily professional use, this is an outstanding product. I use it with a Canon 550EX, and recycle times have gone from from 5-15 seconds with 4 internal AA batteries down to less than one second with the Bolt external pack. Standby power consumption is also reduced. The noise the flash makes while recycling is dramatically reduced. The Bolt also comes with an excellent padded case that can attach to your belt either vertically or horizontally. I'm using Sanyo Eneloop 2000mAh Ni-MH rechargeable batteries. Note: The 550EX requires batteries to be installed inside the flash (in addition to the external pack) to operate the flash's display circuitry and work correctly -- any AA batteries (e.g., alkaline) will do. Wish I had bought one of these years ago!

[0.165 lb] Very Good product!!! Not scared to rant out of power anymore!!

[0.165 lb] The Bolt battery pack is a great alternative to the more expensive Canon packs. It offers thermal protection that is lacking in most cheaper packs. This model comes with a belt case and mounting screw. I am very pleased,and surprised actually, by the quality, beginning with the nice four color box the case was shipped in.

[0.165 lb] Received the battery pack. Since there was one comment that stated the plug on the one he received was recessed and did not work correctly, I examined the plug. Did not find the problem. Put in 4 recharged batteries in the pack (could have put 8 but only had 4 recharged.) Put in the 4 required in my flash. Checked the flash settings and had to change one to flash and external. Put the flash on the camera, plugged in the battery pack and mounted the pack to the base of my 5d battery pack. Started shooting. Found mounting this to the camera was a bit cumbersome as I shot. Recycle was as listed (1 sec +) and shot about 50 shots in fairly rapid succession. No failures. Worked as advertised. Unmounted it from the camera and put it my pocket. Then shot in manual mode, AV mode TV mode and auto. No problems. Would recommend this to anyone.

[0.165 lb] Works great. I'm able to fire my 580EX flash at a much higher rate with this battery pack. The unit also has slots in the case to allow you to attach it to your belt. I don't see any reason to pay a lot more for the Canon battery pack.