An assortment of socket-head cap screws from Hillman. Socket-head cap screws carry a recessed internal socket drive to add strength. They are commonly used on machine parts, manufacturing equipment, and other mechanical applications. Variants in this assortment feature a fine 3/8"-24 thread size. Full assortments of #43520 contain ten (10) refills comprised of Hillman item numbers #2593 - #2596 and #43521 - #43526.