Nikon SD-9 High Performance battery Pack for SB-900
TheNikon SD-9 Battery Packis designed for use with the SB-900 to shorten flash recycling time and increase flash capacity. It accepts 4 or 8 1.5V LR6 (AA size alkaline), 1.2V KR-AA (AA size NiCd), 1.5V FR6 (AA size lithium) or 1.2 AA size Ni-MH batteries.