Knurled head screws are common in applications requiring frequent fastening and unfastening. The diamond knurled surface on these thumb screws provides optimal gripping allowing the screw to be tightened and loosened by hand pressure alone eliminating the need for tools. Made from 303 stainless steel (SS) which is a strong, corrosion-resistant alloy with excellent resistance to heat. 303 stainless steel s designed to be used in high-stress, outdoor and corrosive applications. These SAE screws are available in the following thread sizes: 6-32, 8-32, 10-32, 1/4-20, 5/16-18 and 3/8-16. All screws have right-hand threads. All screws are uncoated. All screws have shoulders and flat tips. These screws will prove to be useful in a wide variety of industries, environments and applications. Specifications: 1/4-20 threads, Head diameter: .750 inches, Head height: .3125 inches, Shoulder diameter: .500 inches, Shoulder height: .1875 inches, Thread length: .750 inches.