For the Medical-Nikkor 120mm-f/4 and the Nikon SB-21 TTL macro flash unit.
External power supply with connecting cord SC-21 and SC-21A
Flash output: M. Nikkor: 450 ; TTL macro 300
Source: 8 alkaline batteries (type LR6)
Dimensions: 149 x 78 x 49 mm
Weight: 325g (ex. batteries)