Use an Allen wrench (hex key) to secure with required torque as needed.
Size: 1/4 inch-20 X 3/8 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.Socket set cap screws have cup points that produce a thin edge that digs into hard surfaces for a secure hold.