Fine craftsmanship is found in the details - things like dovetailed drawers and tightly mitered trim. So you won’t win any craftsmanship awards just because your shelves don’t tip, but you won’t even be in the running if they do! That’s why this jig is so valuable. It helps you drill precisely spaced holes on 32mm (about 1-5/16") centers. Two sets of stops make it easy to offset the holes consistently from the end or side. For the most consistent results, use spring clamps to hold the guide in position. Overall guide length is 23-7/8" with 18 guide holes. The self centering drill has a special nosepiece which mates with the jig, and uses interchangeable 5mm and 1/4" boring bits (Self centering drill, and interchangeable bits sold separately). Made in USA.