The Holland Mushroom Series 5/16" Bolster Plate 2" Size Kingpin is the perfect choice for those looking for a balance of hardness and impact resistance without brittleness. This kingpin is designed to provide ultimate strength and yield characteristics that meet all SAE and TTMA performance requirements. It is also designed to provide exceptional wear for long service. The upper coupler thickness is 0.31", making it a great choice for those looking for a reliable kingpin. With its superior strength and wear resistance, it is the perfect choice for those looking for a reliable and dependable kingpin. FleetPride is your First Click in Heavy Duty®.