Split bite jaw increases grip over standard bite chucks by providing more contact with the bit. Superior gripping force provides high mechanical advantage to convert hand tightening torque into superior bit gripping force. Hammerlock mechanism positive locking mechanism prevents loosening in hammer and other high vibration applications. Anti-lock nut prevents chuck from locking open versatility: models available to fit all 10 mm (3/8 inch) and 13 mm (1/2 inch) variable speed corded and cordless portable drills. Precision operation meet or exceed stringent din run-out and dimensional specifications. Ergonomic design material and surface finish combinations result in increased comfort and performance. Rugged construction constructed of high performance material to maximize durability and performance.