Before You Begin: You need to lubricate the drill guide collar every drill before to prevent the drill bit and collar from overheating. Self Centering Scriber Dowel Jig Kit Vertical Hole Drilling Jig Precise Milescraft Dowel Jig Floating Shelf Bracket With 1/2" X 9" Drill Bit Self Centering Straight Hole Drill Guide For Installing Floating Shelf Hidden Bracket 1 2 X 6 1 2 X 8 Dowel Jig Kit Perfect Woodworking Tools for floating shelf lovers installing the hidden bracket hardware to make their shelf support invisible from outside. Self Centering Drill Guide: Just twist it, fasten it and the Jig will be perfectly centered to drill a straight hole Exquisite 2-in-1 Design: Features a centering doweling jig with a practical center scriber for marking of line 1/4, 1/2, 3/4. Perfect for floating shelf brackets, this jig ensures straight, centered, and repeatable holes-ideal for invisible shelf support installation with professional accuracy Floating Shelf Bracket Dowel Jig Kit with 1/2 x 9 Drill Bit Woodworking Tools