I bought this to feed for my response trigger and it works perfectly. It works in the field for 6-8 hours when never turned off, but to save batteries, i only use turn it on right before shooting. I turn it on and off like a safety and it will work for about twice as long as if its always on. The design is one of the only problems. It is hard to load due to the fact that it is long and skinny.
This works perfectly for an e-grip or a response trigger, but has a bad design and is hard on batteries.