Wider Clamping RangeThe clamping range of our dowel jig is 0.4" - 6.7", which is easily adjustable and can be used to clamp boards of different thicknesses. It's perfect for making shelves, cabinets, tables, chairs, repairing doors and more. Wide ApplicationThere are 4 drill guide holes along the top of the doweling jig, 2 holes accept threaded bushings that can be replaced with sizes 1/4", 3/8" and 5/16". The other 2 holes directly accept 7/16" and 1/2" drill bits, their inner walls are smooth, no need to use a drill sleeve, and you can drill directly with a drill bit. This makes it a versatile tool for a variety of woodworking DIY projects. Precisely Positioned DrillingThe doweling jig for woodworking is machined by precision computer numerical control. When you turn the middle bolt, the aluminum jig on both sides will tighten at the same time to realize center positioning automation, and the center error is controlled within 0.002". The positioning is more accurate without leaving any gaps, precise drilling can be easily achieved. Strong & DurableThe splints on both sides of the self centering dowel jig is made of industrial-grade aluminum alloy, and the surface is anodized to prevent rust and is strong and durable. The drilling guide center is made of steel, which has been heat treated to have higher strength and resistance to deformation. This will allow for a longer service life.