Grub screws are short, headless screws with a hex socket. They are primarily used to prevent rotation between two parts. A grub screw is inserted into a threaded hole in one part and then tightened against a flat surface on the other part, preventing the two parts from turning relative to each other. They are commonly used in machinery, automotive components, and other applications where rotational stability is important. These Assortment Kits provides multiple sizes of product in a convenient utility box.