These professional quality carbide tipped bits are designed to drill flat-bottomed holes. Use with a drill press, or with a hand drill and our exclusive JIG IT® Drill Guide (#91981, sold separately). All Forstner bits have a 3/8" diameter shank and require a 3/8" stop collar if used with the JIG IT Drill Guide. These long shanks are 3-7/8" long. Features: Bits feature carbide tips for enhanced durability Designed with spiraled flutes to allow for fast chip removal All bits have a 3/8" diameter shank