10 pack/pieces knurled head solid brass thumb screws with straight shoulders and flat tips The 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. Knurled head screws are common in applications requiring frequent fastening and unfastening. Available in the following SAE thread sizes: 6-32, 8-32, 10-32, 1/4-20, 5/16-18 and 3/8-16 Made from solid brass which is a corrosion-resistant alloy.