Made in Japan this Anastigmat projection lens has a 4" focal length. The front lens clear diameter is 1-1/4" and the rear lens clear diameter is 1-1/8". This multi-element assembly has a beautiful pinkish/purple anti-reflective coating. The housing is 3" long by 1-7/8" diameter front diameter and the threaded diameter is 1-11/16". These have been in storage for some time, so the internal optics might need to be cleaned.