An assortment of metric external and internal retaining rings from Hillman. Retaining rings are used to secure parts onto shafts. They fit into grooves in the shaft for a snug fit. Metric retaining ring variants included in assortment run M10 thru M25 in diameter. Full assortments of #45615 contain sixteen (16) refills comprised of Hillman item numbers #45616 - #45631.