Keyless Drill Chuck Metal Heavy Duty 1/2-20 UNF Threaded 2-13mm Capacity Tool
(1/2 - 20 is the definition of thread specification. Specification: 1/2; number of threads (T): 20. Drill Chuck Keyless Drill Chuck Keyless Hand Drill Chuck 1/2‑20UNF Mount 2~13mm Self Tighten Drill Chuck for Multiple Purposes. ).