Bosch (Older Style) Progressor Quick Change Hole Saw Arbor Pilot Drill Bit HSS-G
(Suited only to the older style Bosch "Powerchange" arbor's. This pilot is slightly thinner and shorter than newer plus version pilots and the hex shank is longer.). Hex shank width: 1/4" (6.35mm). Approx drill width: 6mm.