Beautiful multi-element lens assembly with coated optics. Compugraphic part# 56645 manufactured by Kowa. We think these were designed to be used with photo typesetting machines. If you've got one then this is a great bargain. If not, take it apart for the optics. Measures 2-3/8"long x 1-1/32"diameter, with a 1-13/16"diameter 3-hole mounting flange (3/16" holes). Clear lens diameter is 3/4".