1/2" Professional-Duty Hand-Tite Keyless Chuck (3/8-24). The Jacobs technically advanced keyless chucks are the most exciting innovations in drill chucks ever. They significantly reduce bit changeover time and boost productivity. Based on an exclusive patented design. the Jacobs keyless chuck achieves higher gripping torque than standard keyed chucks, and there is never a key to misplace. They feature a nonrusting, high-performance body with a unique sure-grip sleeve for maximum user comfort and hand tightening efficiency.