1/4 inch Hex Shank Adapter to 3/8 inch 24UNF Drill Chuk with Lock Screw. Features Reverse Thread Screw to Lock the Chuck. Quick connect keyless chuck to any 1/4 inch hex drive tool. Compatible with locking steel keyless chuck of 3/8-Inch-24 UNF thread. Screw head fits perfectly into any keyless chucks (3/8-24 UNF). Hex End Used for Increase operator productivity and convenience by speeding bit changeovers.