1/2" Keyless Drill Chuck Replacement 1/2 x 20 UNF 13MM fits most drills 1/2 inch Keyless hand-tight three jaw design fits most drills with 1/2" shaft 5/64" to 1/2" capacity, Hardened jaws Drill chuck easily replaces your defective drill 1/2 - 20 UNF mount, Easy Grip body for increased drill chuck closure torque. Serrated chuck for improved drill bit grip under most severe loads