Nikon SD-9 Battery Pack
The Nikon SD-9 Battery Pack plugs into the SB-900 and SB-910 Speedlights (rentable separately) and, with the help of up to 8 additional AA batteries, increases the number of flash pops you can get in a session up to 520 with a 1-30 second recycle time (results vary depending on age and type of AAs used). Note that you must still keep 4 AA batteries inside your Speedlight in order to get the benefits of this battery pack. This pack is a great addition to your flash setup for long-lasting events.
There is no manual for this product.