This 3/8" diameter combination edge and center finder helps you locate work on your mill. The edge finder end has a 0.200" diameter cylinder to quickly find the edge of a work piece. The center finder end tapers to a point to locate holes. The edge and center finder is hardened and ground all over. Simplify using the edge finder with an edgefinder adapter, 66-025. Most times, the shank of the cutter you intend to use is not the same size as the edge finder. You would have to use one collet to hold the edge finder, align the work, and then switch collets for the mill work. The edge finder adapter eliminates swapping collets - which saves time and improves accuracy.