Guardrail bolts are what’s used in highway barriers and other safety fences, which means these bolts are durable and reliable. A guardrail system is what absorbs the force from a crashing vehicle.

HDG or Hot dip galvanization means this nut underwent a process that will prevent corrosion. It started with chemical cleaning and ended with the coating process.

Grade 8 bolt strength or class 8.8 means it’s high strength. This classification means the nut is medium carbon steel, quenched and tempered. All sizes below 16mm means they have a Proof Lead of 580MPa, minimum Yield Strength of 640 MPa, and minimum Tensile Strength of 800 MPa. On the other hand, those that are more than 16mm above have a Proof Lead of 600MPa, minimum Yield Strength of 660 MPa, and minimum Tensile Strength of 830 MPa.