Shape the full edge of a workpiece with a bullnose radius bit. Ideal for shaping stair treads, window sills, table and counter edges, shelves, and making moldings. The "nose diameter" (M) is the thickness of stock that can be nosed, i.e., given a full 180-degree roundover. Flats at top and bottom of the cutting edges create fillets on stock thicker than the nose diameter. Must be used with an edge guide on handheld routers or the fence on a router table.