Gib Head Keys are tapered and notched machine keys used on power transmission shafts to tightly secure pulleys & gears to the shaft. Variants included in this assortment range from 1/4" to 1/2" in diameter and from 1" to 3" in length. Full assortments of #45982 contain twelve (12) refills comprised of Hillman item numbers #400068 - #400079.