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 1/4"-20 thread size. Full assortments of #3209 contain eight (8) refills comprised of Hillman item numbers #3210 - #3217.