SAF Holland 2″ Double Spool Kingpin. Part number KP-AAR-880. 3/8″ Bolster Plate. Made from 4320H or 4718H alloy steel for strength and durability. Meets or exceeds the performance requirements of the Truck and Trailer Manufacturers Association (TTMA) and the Society of Automotive Engineers (SAE). 15287 L4B2