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 1/4"-28 thread size. Full assortments of #43501 contain ten (10) refills comprised of Hillman item numbers #2587 - #2589 and #43502 - #43508.