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 coarse 3/8"-16 thread size. Full assortments of #3227 contain eight (8) refills comprised of Hillman item numbers #3228 - #3235.