Shimano 600 downtube shifters friction clamp on

Great condition, Shimano 600 downtube shifters friction clamp-on. Suitable for a 6 x 2 drivetrain. This was one of the last friction version before the series turned into indexed shifters. 

Shimano 600

Shimano's second in line road group set, introduced in the 1970's as the 600.  The 600 group became the 600 Ultegra and then dropped the 600 altogether to become the modern Ultegra groupset.