This item is an ideal and in my view, neccessary accessory for the Nikon D90 DSLR. It vastly improves the handling and prolongs the available power for extended shooting (I've heard some reviews claiming 5000 JPEG shots but I haven't got that far myself yet!) Cleverly, it uses the two installed batteries individually so it'll exhaust one battery before it starts drawing power from the second. And if you are so prolific a photographer that you manage to run both down, there is a cradle included which holds six AA batteries! I reckon the memory card will fill up before the power goes...There is also a shutter release button on the battery grip which makes shooting in portrait a breeze - oh, and it's lockable so you won't accidentally fire off any shots due to clumsy handling. This unit is solidly built, practical and comfortable to use, just as you would expect from a premium company like Nikon. Sure, it's more expensive than other so called 'compatible' units but I'd much rather have an accessory which I know is 100% compatible with my expensive DSLR than risk damage due to a cheaper third party product. An all round excellent product which I would highly recommend.