Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: Will this work with battery pack?
Document: While this appeared to be an exact copy of the Nikon battery grip, it simply did not work.My advise...if you are spending a lot of money on a great Nikon camera, buy the Nikon part that goes with it.
I purchased this grip based on the fact that it is magnesium alloy construction and 1/3 the price of the Nikon MB-D12. I have owned two other grips for other bodies in the past, they both felt cheap, they rattled and they did not fit perfectly to the camera causing lost battery connection. This grip is practically identical to the Nikon, fits absolutely perfect to the body, no flex, no lost battery connection, all controls work flawlessly and has a quality build.
The Kaavie Battery grip is very well made, fits perfectly on the Nikon D800, and offers outstanding ergonomics. However, when using the battery grip, I have noticed some anomalous behavior with my camera, such as failing to get the custom white balance to work, not being able to access the menu system, failing to autofocus, and occasional camera lockup. Removing the Kaavie battery grip eliminated these issues. These glitches occurred randomly, but happened often enough to make grip unusable.
The location of the buttons and function are great. The only reason I don't give it a '5' is the same reason I don't give other cameras and equipment I own a '5' -- not waterproof. I have ruined 2 cameras, 2 lenses and one battery pack so far so far due to accidental water exposure. (My daughter-in-law ruined one when she had to make the decision to save the camera or my granddaughter who was being swept downstream in a river.)
I fiddled with it and removed and reattached it and still nothing. I then jiggled the on/off lock switch that surrounds the shutter button and it came to life. Unfortunately my camera was beeping and the focus point in the viewfinder rapidly and continually moved horizontally. I turned off the camera and the problem abated and the grip seemed to work. I turned it off and on, took it off and on.
Grip has good fit and finish. Very satisfied. Excellent bargain and a great alternative to the overpriced nikon OEM battery grip.
But making these refinements could raise the product from "nearly perfect" to, basically, "perfect". Overall, I feel the Kaavie battery grip for the D800/D800e is an "exceptional" product, just as they claim in the description.
tried it and I lost. Always shutting down and you need to take the battery out over and over  just to keep it working yes it's a a piece of polo  never buy it don't even try it. Definitely not recommended mine 2 star if possible!!! !
Was nervous about ordering, but completely satisfied. Fits snugly to body, battery tray seats firmly and without rattles. Button and dial quality not as high as oem but worth $120. Long-term durability unknown.
The grip is of good build quality. It doesn't feel cheap and mounts solid to the body. My problem is that while this grip is connected all controls of my D800e will randomly stop functioning. The only solution is to take the battery out, wait a second, then put it back in. It's really frustrating and I have missed shots because of it.
Answer: Yes, it works great with the Nikon D800 and D800E.  It contains a place for an extra battery in addition to the battery in the camera, which extends the number of images you can take with a full charge.