Description: This square hole drill cannot be used with electric drills, it must fit for square hole drilling (mortise and mortise machine) to use the drill corner.Standard flutes are designed to facilitate the removal of wood chips and increase efficiency. Exquisite blade grinding process for drilling, edges are sharper and more durable.Specifications: Material: High Speed Steel; Color: Image Display Size (Optional): 0.4 inch (10 mm) / 0.6 inch (16 mm) Length: 8.1 inch (203 mm) (Diameter 10 mm) / 8.1 inch (208 mm) / 0.6 inch (166 mm); Package Includes: 1 x Square Hold Drill