This bayonet mount lens hood exposure meter was made by Rollei for their line of TLR cameras and is a beautiful example of the clever engineering of the analog era.
Meter folds in to hood for safe keeping while not in use. Fold the meter out until it clicks in to place, then go ahead and take a reading. If it is not very bright out, you can open the white plastic cover over the selenium cell and click it in to place at the back of the meter. When finished, pull back the lever and it springs back in to place.
To take a reading, observe where the needle falls in the scale and rotate the dial until the red needle lines up with the white needle. The settings shown on the dial can now be used to get the perfect exposure.
This hood will fit most Rolleicord or Rolleiflex cameras that have this bayonet mount at the lens. There is some information out there about this bayonet also fitting some Yashica TLR models but this has not been verified by us, so we make no claims as to cross-brand compatibility.
In very good condition with no damage and only some signs of normal wear to the bayonet threading. Meter works and is accurate, but only as accurate as a nearly hundred year old piece of technology ever was. Comes with a suede drawstring bag, but it is not the original case.