An assortment of stainless steel 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 come in coarse 5/16"-18 and 3/8"-16 thread sizes. Full assortments of #3258 contain twelve (12) refills comprised of Hillman item numbers #3259 - #3270.