Nikon MB-N10 battery pack additional information from Nikon USA:
The MB-N10 is a Multi Battery Power Pack for the Z 7 and Z 6 full frame mirrorless cameras (cameras sold separately). It is designed to add additional shooting time versus just using the battery in the camera alone. The MB-N10 may increase the length of shooting time up to 1.8x* (*CIPA standard) more than using just the camera’s battery. The MB-N10 is designed with the same weather sealing and modern design of the Z cameras and affords photographers a well-balanced feel when a long telephoto lens is on the camera.
The MB-N10 can accept two EN-EL15b or EN-EL15a/EN-EL15 rechargeable Lithium-ion batteries, each housed in its own battery compartment. For convenience, the batteries are hot-swappable, which means that you can replace one while the other continues powering the camera. This is beneficial for video, interval and time-lapse shooting. With two batteries, power is first drawn from the battery in chamber A until it is depleted, and then the unit draws power from the battery in chamber B.
Other features include battery power level displays for each battery, a socket for connectivity to a tripod and the ability to use the optional EH-7P Charging AC Adapter to charge the EN-EL15b batteries while inserted into the unit, whether its attached to the camera or not.
Stills: Measured at 23 °C/73.4 °F (±2 °C/3.6 °F) with a NIKKOR Z 24–70mm f/4 S lens under the following test conditions: one photograph taken at default settings once every 30 sec.
Movies: Measured at 23 °C/73.4 °F (±2 °C/3.6 °F) with the camera at default settings and a NIKKOR Z 24–70mm f/4 S lens under conditions specified by the Camera and Imaging Products Association (CIPA).
Hands-on video:
Pictures via PhotographyBlog
Nikon MB-N10 pre-orders: Adorama | B&H | Park Camera | WEX | Camera Canada