The MB-D14 is a Multi-Power Battery Pack for the D600.
The MB-D14 Multi-Power Battery Pack can be powered either by six AA batteries (Alkaline or Ni-MH or Lithium), or EN-EL 15 rechargeable Li-ion batteries. To use the MB-D14 with AA batteries, use the MS-D14 AA Battery Holder. When using EN-EL15 batteries to power the MB-D14, use the MS-D14EN Battery Holder.
The MB-D14 is equipped with a shutter-release button, AAE/AF lock button, multi selector, and main- and sub-command dials for improved operation when taking photographs with the camera vertically oriented.