Trailer King Pins From Buyers Products Provide Strength And Reliability In Coupling Your Fifth Wheel. They Are Forged From Aisi 8630 Steel And Heat-Treated To Maintain A Hardness Of 302-363 Bhn And 150,000 Psi In Ultimate Strength. They'Re Available In Several Weldable Bolster Plate Thicknesses. An 8 Hole Bolt-On Version Is Also Available.