Professionals worldwide prefer Proto Industrial Tools for their outstanding quality durability and dependability. Professionals for heavy-duty industrial applications including auto-manufacturing plants steel and airplane manufacturing chemical plants refineries general manufacturing transportation and fleet maintenance for trucking transit and aircraft use Proto Industrial Tools. With a global distribution network Proto Industrial Tools are available on-the-job anywhere in the world. Opening Size: 5/16".Opening Type: Hex.Shank Length: 2-7/8".Overall Length: 6-11/16".Shank Type: Round.Measuring System: Inch.Material: Alloy Steel.Finish: Chrome.