Zinc Cotter Pins are used to secure two items together with the use of a common hole. Place the cotter pin in the hole. The bulbous head stops the pin from moving all the way through. Included parts come in 3/16" and 1/4" eye diameter variants and run 2" to 4" in length. Full assortments of #45681 contain eight (8) refills comprised of Hillman item numbers #45682 - #45689.