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. Variants included in this assortment range from M1.6 to M2.5 in diameter. The included screws run from 4mm to 16mm in length. Full assortments of #43627 contain sixteen (16) refills comprised of Hillman item numbers #4297 - #4302 and #43628 - #43637.