Big Horn 19138 1/4" centering bit (can be used with Pin Jig). Precisely spaces shelf pin holes 1-1/4", 32mm or 64mm from edges. Index the 20" jig with a shelf pin for use with any length shelf. 1-1/4" self centering bit included. This self-centering bit provides dead on accuracy of shelf pin placement for your project when used with any appropriate template. Standard 1/4-Inch hex shank will fit power bit and quick change drill chucks. Our bit assembly is designed so the bit is removable when the time comes that it needs to be sharpened. 1/4-Inch self-centering bit can be used with Big Horn 19651 Pin Jig and Bit (sold separately) or other templates with 3/8-Inch guide holes.