High speed steel extension drill bits for use in general drilling applications where extended reach is necessary. 6, 12 or 18 inch length drill bits. Shank diameter equal to drill diameter. Fractional and Number sizes. The 135 degree Split Point eliminates walking at the drill point and reduces thrust. Long length drill bits allow for extended reach while drilling, or extended drilling depths. They are available in varying materials and designs for a wide range of drilling applications. Extension drills have a longer shank and are used to extend reach for hard to access drilling applications. Extra length drills have longer flutes and are meant to allow for deeper drilling, as well as extend reach.