Bahco Expansive Bits are capable of drilling a wide range of shallow hole sizes in wood. The MD series have round shanks and are suitable for use with power tools. Made from a single-piece of drop forged steel. Head and adjustable cutters hardened and tempered. Locking screw zinc plated with hexagonal head with slot. With expansive bits it is possible to drill a full range of diameters with the same bit, in wood. Adjustable with screwdriver or wrench.