This bit is essentially a plunge-cutting straight with a shank-mounted ball-bearing pilot. It is a versatile bit, useful for template/pattern routing of parts, joints, and internal cuts, and can be used in handheld and table-mounted routers. The template is attached to the workpiece, and the pilot bearing rides along its edge as the cutting edges rout the workpiece, forming an exact duplicate of the template. With a handheld router, the pattern is on top of the work; with a table-mounted router, the pattern is underneath the work.