Spline DD-BU to 1-1/4" M Core Bit to Drill Adapter by BLUEROCK Tools Model #9 fits HILTI Spline Style end fits Spline (DD-BU) style drills 1-1/4" 7unc Male Threaded end fits BLUEROCK Wet type core bits as well as other compatible threaded coring bits Solid all metal construction The 2.5" Core Bit is shown for scale and not included with this adapter. Please see our separate listing for core bits and core bit packages Spline DD-BU to 1-1/4" M Core Bit to Drill Adapter by BLUEROCK Tools Model #9 fits HILTI. Spline Style end fits Spline (DD-BU) style drills 1-1/4" 7unc Male Threaded end fits BLUEROCK Wet type core bits as well as other compatible threaded coring bits Solid all metal construction The 2.5" Core Bit is shown for scale and not included with this adapter. Please see our separate listing for core bits and core bit packages. HILTI is a registered trademark of Hilti Corporation and is only used for product identification purposes.