Others will be a lot more clued up than me but I believe that Rolco were mid market watches marketed by Rolex. Intended to be just as reliable but at a more moderate price. A lot of dealers now claim that these are Rolex pieces but the movements were, I believe, supplied to Rolex who may have modified them slightly. That would make them more of an olden Tudor type watch. Age wise I would suggest 1920-30’s. A very nice piece to have and great that it’s still working.