Very early Soligor lens made by Komura (Sankyo Kohki Komura) (Soligor was a brand of Allied Impex of New York). Dates from 1956-1959, most likely. This was one of the pioneering products of the Japanese third party lens industry, along with those of Arco, Zunow, Sun, Kyoei and Fujita. Earliest reference to this type I have found was in Seymours Exakta catalog of 1956. Usually found in importers brands such as Soligor, Juplen, Peerotar and Spectra Coligon, and only rarely as a Komura. These are quite scarce in M42, more typical to find them in Exakta mount.