Nikon MB-D12 Multi Battery Power Pack
Supplied with MS-D12EN for EN-EL15 Rechargeable Li-ion Battery (sold separately) and MS-D12 for 8 AA batteries (not included); accepts 1.5V LR-6 (Alkaline), Lithium (FR6), Ni-MH (HR6) or Ni-Mn (ZR6).