The Holland Mushroom Series 2" x 5/8" Bolster Plate King Pin is designed to provide maximum wear resistance and high impact resistance. The alloy selection and controlled hardening process ensure that the king pin is able to withstand the toughest conditions. The heat treatment provides the best balance of hardness and impact resistance, while the excellent welding characteristics make installation or replacement easy. The king pin is also tested with ultrasonic testing to ensure the integrity of the kingpin below the surface. FleetPride is your First Click in Heavy Duty®.