Knurled cup point Set Screws have an externally knurled cup point that locks the set screw in place and resists loosening and deformation under high vibration. Knurled cup point set screws are used both in poorly tapped holes and to locate gears and pulleys on shafts. Hex socket drive types have a hex-shaped recess in the head and are driven with hex keys or hex socket bits. The driving surface is protected from external damage and provides six sides of contact surface for added torque. Alloy steel is the strongest of all steel types. It has high tensile strength and offers excellent resistance to wear, fatigue and galling.