CMT 537.400.31 Forstner Bit, 40mm (1-37/64-Inch) Diameter, 10mm Shank 3-35/64-Inch Overall Length, Right-Hand Rotation. 2 spurs, 2 precision ground cutting edges, long-lasting cutting performance. Drill precise flat bottom holes with no chipping in any thickness of soft wood. For drilling holes in any direction and making arched openings. For drilling partially overlapped flat bottom holes or niches used to fix supports.