This condenser assembly was sold by Hugo Meyer & Co., but was originally made in Germany. The box is marked "Goerlitz-New York". Lens diameter is 26mm, focal length is 25mm. The assembly is 45mm x 30mm x 16mm thick. Under the lens is a 12mm opening with a tightening screw underneath, so may have been for some type of smaller optical bench. Unused in the original box!