This is/was a self-powered selenium cell based meter. The rectangular piece with two pins at one end is a
booster cell. There are diffusers to use for incident light metering. This began to get a bit intermittent
(at one time correctable by pushing on the photo sensor!) and that and the desire for better low level measurments led me to
buy the Lunasix. A recent check discloses the Waltz is apparently even more intermittent and nearly (but not quite!) dead.