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 affords an easily accessed vertical shutter release button, AAE/AF lock,
and dual command dials.