>There are little things to look out for on aftermarket >grips...build quality being one, but another is that the >battery tray does not positively hold the battery with >anything other than a friction click. The Nikon brand has a >detent in the tray that pops up to hold the battery in place. >
My 3-rd party grip has the same pop-in feature.
Also, 3-rd party grips may use slightly different battery holders... they're not interchangeable with OEM.