When you're serious about building your own custom rods, this tool is indispensible. The Spine Finder makes finding the proper spine quick, foolproof, and hands free. Holds the blank in the correct position so the spine can be easily, and accurately marked. Finding the correct spine placement is critical in achieving optimum performance from a rod. Comes complete with two weights, a 4 oz. and a 6 oz. for use with different size blanks. Redwood construction for a lifetime of use.