IBX1615 Features: * Designed to remove broken studs, bolts, socket screws and fittings for high torque applications * Aggressive left hand spiral design for extra gripping power * Hex head size: 1/2" * Bolt diameter: 7/16" * Recommended drill bit diameter: 1/4" * Hex Head Multi-Spline Screw Extractor - 1/4"""" Warranty: * Lifetime warranty does not cover abuse