1/4 inch hex shank adapter to 3/8 inch thread 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.for 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.