3; ASME B1.1. This fastener is headless and contains an internal hex drive.Size: 1/4 inch-20 X 5/16 inchHeadless screw that sits flush or below the surface once installedInternal socket drive requires Allen wrench (hex key) to installInstalls into an internally threaded hole to hold an object into placeOften used in machinery to secure gears to shaftsThread Type: Coarse, Thread Class: UNC-3A, Point Style: Cup PointSpecification(s) Met: ASME B18.
0996, Metric, Drill Bit Point Type S Thinning Point, Non-Coolant Through.Jobber Drill Bit, Drill Bit Size 2.53 mm, Drill Bit Point Angle 130 Degrees , High Speed Steel, Decimal Equivalent 0.