Extensions can be added to both the 780XT and 78XT Series, enabling internal measurements in deep hole bores. (Multiple extensions can also be used.). 8" Length.
Internal Micrometer Extension, 2-12" (50-300mm), 8". The Starrett Internal Extensions for 78 Series Internal Micrometers includes 2-12" (50-300mm) sizes, 6" extension size, and fits models 78XT/780XT/781XT-2 thru 12. Extension 6"/150mm Long for use with 78/780/782 -2 thru 12.