The Starrett A17-38E locking arbor with extra length high speed steel pilot drill, suitable for use with the extended cutting depth of our Fast Cut Multi Purpose Hole Saws (MPH). 8.75mm (11/32") hex shank, fits hole saw diameters 32-159mm (1.1/4"-6.1/4"). The arbor locks tightly on the saw eliminating vibration and is invaluable on exceptionally tough jobs and production runs.