Greenlee 66PT-5/8 Specifications: Overall Length: 18" Twist Length: 15" Hole Diameter: 5/8" Hex Shank: 7/16" Greenlee 66PT-5/8 Features: Improved cutting edge provides 30% longer life span. Patented new design for improved cutting and cleaner holes. Self-feeding screw point draws bit through wood. Unique patented design cutting angle - smoother starts, reduced cutting loads. Made of super tough, heated-treated steel; cuts through nails and provides longer life.