A Hillman assortment of grade 5 hex cap screws with 5/16"-24 fine screw thread. Hex cap screws, or hex bolts, are perfect for most applications in which a stronger, sturdier bolt is desired. A common feature on hex cap screws is a washer surface directly under the head which creates a better seal. The assortment features hex cap screws in variants featuring 5/16"-24 fine screw thread in lengths ranging 3/4" thru 4". Full assortments of #1673 contain eight (8) refills comprised of Hillman item numbers #1674 - #1681.