The Zeikos Power grip for the Nikon D300 & D700 is the perfect solution for doubling your shooting time. It holds either 1 EN-EL3E Lithium-Ion Rechargeable batteries or 6 AA batteries. It has a vertical firing release with a lock and dramatically improves stability. It has a 1 year warranty.
a) Zeikos ZE-NBG300 Professional Multi-Power Pack for Nikon D300/300S & D700
b) 2 Replacement EN-EL3E Rechargeable Battery Packs