Shelf Pin Jig Drill Bit (5mm) This 5mm high-speed steel drill bit replaces the bit that comes with the 5mm Kreg Shelf Pin Jig. Also works with the 1/4' (6mm) Kreg Shelf Pin Jig. This high-speed steel drill bit allows you to drill 5mm shelf-pin holes with the Kreg Shelf Pin Jig. This bit features an ultra-sharp brad-point tip for exact centering and clean cutting, so that you'll get smooth holes for shelf pins. The 1/4' hex shank tightens easily into standard drill chucks, and fits quick-change chucks and adapters.