Hello Kyle: As Willis mentioned F.O.K. stands for Farwell-Ozmun-Kirk. They were an enormous hardware wholesaler located in downtown St. Paul Minnesota across the street from the St. Paul Union Depot. They distributed hardware all over Minnesota, Iowa, Wisconsin, the Dakotas, and Montana. They later franchised the O.K. Hardware stores located in many small towns across the upper midwest. Your lantern probably originally had an F-O-K embossed globe which they used on their older pre-1920 lanterns. They are tough to find so keep an eye out.