Installing Floating Shelves: The drill bit size is 1/2Inch x 11.8Inch, suitable for installing floating shelf brackets and hidden shelf brackets less than 9 inches; Ideal tool for installing hidden brackets;Extended bit size fits most common floating shelf sizes. Multi-purpose: Our dowel jig kit can not only drill 1/2-inch holes for installing floating shelves,hiding brackets,mantels,and can also drill 1/4,5/16,and 3/8 inch holes for specific requirements in DIY, drilling,and other woodworking tasks. Drill Perfect Holes Easily: The unique positioning center design of the self centering dowel jig allows you to drill with both hands by simply attaching the screw,reducing wrist stress and allowing novices to easily drill straight and perfect holes. Strong and Wear-resistant: Dowel jig is made of aluminum alloy,and the guide ring is made of high-quality stainless steel;It is strong, wear-resistant,and heat-resistant;It can withstand multiple drillings with high-speed drills and is durable. Meet Diverse Needs: Value set includes 1 dowel jig, 4 drill sleeves (6 mm,8 mm,10 mm,13 mm),4 drill bits (1/2Inch,1/4Inch,5/16Inch,3/8Inch), a must-have woodworking set for woodworkers,construction workers,and DIY wood enthusiasts. Colour:As Shown Material:aluminum Package Contents: 1 * Dowel Jig Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.