Amana 49521 Carbide Tipped Corner Rounding 7/8 R x 2-1/4 D x 1-1/4 CH x 1/2" Shank w/ Lower Ball Bearing Router Bit 2 Flute & 4 Flute The router bits found on this page include the miniature 3/16" and 1/4" diameter ball bearings for routing tight spaces, the In-Tech insert replacement knife series, diamond tipped (PCD) bits as well as the standard 1/2" diameter ball bearings. The basic edge-forming bit, the corner-rounding bit rounds an edge to a given radius. The tool is shouldered to cut a fillet. The cut can be used to ease edges, as a simple profile, or as a part of a complex one. Also known as roundover, rounding over, and quarter-round. If a smaller pilot bearing is used, a second shoulder can be produced, in effect making the bit a beading bit.Tool #DRB-504 is excellent for composite panels, fiberglass, fiberglass PCB board, fiberglass reinforced composites, lightweight composites, custom composite materials, fiber-reinforced urethane and fiber-reinforced structural foam floors.