Metric 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 run M1.6 thru M6.3 in eye diameter and 12mm to 50mm in length. Full assortments of #44956 contain sixteen (16) refills comprised of Hillman item numbers #44957 - #44972.