THREADED HD Mag Drill Chuck - 5/8" For Magnetic Drill - Heavy Duty 5/8" (16mm) Drill Chuck for Mag Drills Comes With Chuck Key Use with 3/4" Weldon Shank Bottom Taper: 1/2"-20 UNF (Screw Type) Bit holding Capacity: 3-16mm (up to 5/8")