Sonnax high clutch steel S019715HK-150 is a severe-duty upgrade for use with Sonnax 24-lug clutch drums in GM Powerglide racing applications. These Kolene® steels have 24 external teeth, double the normal amount. With twice the number of teeth engaged, wear will be reduced dramatically. Combining anti-drag tabs and turbulator holes significantly reduces the heat generated when the clutch freewheels.