Binder-Head Nylon Machine screws and nuts are used in conjunction with one another in order to fasten metal parts together securely. To ensure proper fit and quality of life, make sure to use machine screws with nuts of similar thread size and finish. Thus, nylon machine screws should be used with nylon hex nuts. Screws in this assortment come in variants ranging #4-40 thru #8-32 in coarse screw thread size. Included variants range 1/4" to 2" in length. Full assortments pf #59463 contain sixteen (16) refills comprised of Hillman item numbers #59464 - #59479.