Unitron is a US-based company and distributor of optical instruments including stereo microscopes and accessories, binoculars, and classic brass telescopes. The company was founded in 1952 by Lawrence A. Fine as the United Trading Company and located in Boston, MA. He registered the UNITRON trademark in the United States for first use in commerce in February, 1952. The company started out importing smaller that were manufactured by Nihon Seiko of Japan. By 1961 Unitron expanded the product line to include 5" and 6" models that were suited for observatory use. A very small number of the 5" and 6" models were produced. Several of the 6" Model 620's remain operational at observatories to include: Rafes Urban Astronomy Center, Denton, Texas; Castleton State College, Castleton, Vermont, Ferris State University, Big Rapids, Michigan, and the University of Connecticut, Storrs, Connecticut.