MATERIAL ALUMINUM OIL SEAL SURFACE NO 12.94 157012-19 This front drive hub nut is made from aluminum and is for use with a RCD 6" blower snout.

MATERIAL STEEL OIL SEAL SURFACE YES 47.23 157012-25 This front drive hub nut is made from steel and has oil seal surface, it is for use with RCD 8" and 10" blower snouts.