The Nikon MB-D14 Multi Battery Power Pack gives you a firm, steady grip on the D600 or D610 that you'll appreciate with longer lenses or low shutter speeds. The grip also gives you greater control when in the vertical or portrait position. Instead of grappling for control on the camera body, the grip provides an easily accessed vertical shutter release button, AAE/AF lock, and dual command dials.
And when it comes to power, the MB-D14 is a real omnivore, allowing it to consume power from a variety of sources. Nikon has provided you with an MS-D14 AA Holder permitting you to use Ni-MH, Alkaline, or Lithium AAs as well as an MS-D14EN Battery Holder for use with an EN-EL15 battery. 6 AA Alkaline batteries will give you about 450 shots while the optional EN-EL15 battery will give you an impressive 1,800 shots. That's a long time before recharging.
Note: Batteries not included