In the box: - Brand New BL-5 Battery Chamber Cover x1 (Not including battery) Specifically designed for D800 D800E D810/D500/D850. For use with MB-D12/MB-D17/MB-D18 Multi-Power Battery Pack and EN-EL18 Rechargeable Li-ion Battery to protect the battery chamber. The BL-5 is a battery chamber cover for use when powering the D800 D800E D810/D500/D850 D-SLR with the MB-D12/MB-D17/MB-D18 Battery Pack and using the EN-EL18 rechargeable lithium Ion battery.