It's a 1991 model, manufactured in Taiwan during January 1991. According to my literature, the Master TG was Shimano 105SC.with brifters. The 600 Ultegra model in 1991 was the Prevail TG. Those are 600 Ultegra brifters. A great deal at $110. FYI, MSRP was $714 US and the TG stands for the TIG welded construction.