The Nikon MB-D17 Multi Battery Power Pack is a battery grip designed for the D500 to increase the number of shots per charge that you can get. It features a shutter release button and Fn button for ease in vertical shooting.
The Nikon MB-D17 can be powered by eight AA batteries or by a single EN-EL15 or EN-EL18a lithium-ion battery. When using the MB-D17 with eight AA batteries, use the MS-D12 battery holder; when using the EN-EL15 battery to power the MB-D17 use the MS-D12EN rechargeable li-ion battery holder. The BL-5 battery chamber cover is needed when using the EN-EL18a to power the MB-D17. The MB-D17 can also be powered via the EH-5b AC power adapter using the EP-5B power connector.