[High Precision] Self centering dowel jig are machined by precision Computer Numerical Control machines.When you turn the middle bolt, the aluminum jig on both sides will tighten at the same time,the board will be clamped evenly so that the position to be perforated is in the exact center. 㐲ofessional Productsㄲilling guide positioner different holes 1/4 inch | 3/8 inch | 5/16 inch | 7/16 inch and 1/2 inch and three different drilling sizes 1/4 inch | 5/16 inch and 3/8 inch require very little operation to meet more professional requirements. ㄲill Auxiliary Marker Line㔨e engraved line seen in the front view is used for direct alignment at the center. The alignment can be done visually, making it easier to use. ㅸcellent Quality㔨e aluminum surface is anodized for vivid color and does not easily leave scratches. The iron in the center is treated with alkaline oxidation and the screws are chrome-plated to prevent rustingＭore stable. 㗩dely Used㉤eal for some DIY project, Ideal for some DIY projects, such as putting two boards splicing together.Making closet shelves that require flat panel connections,make some shelves, cabinets, desks, breakfast tables, blinds in the garage, repairing doors that children have accidentally destroyed, make floating shelves,installing railings.