Nikon SD-8A Hi-Performance Battery Pack 4729 (Stock of UK)
It can be used with the SB-11, SB-22, SB-25, SB-26, SB-27, SB-28, SB-28DX, SB-80DX, & SB-800 Speedlights, as well as the SK-6A Power Bracket. Batteries must be place in the flash in order to operate.