Carriage bolts feature a smooth, rounded head and a square shoulder beneath it that grips the material to prevent spinning while the nut is tightened.
Nominal Size: 5/16"
Thread: 18 TPI (Coarse)
Length: 1"
Thread Length: Full
Material: Steel
Finish: Zinc
Head Style: Carriage
Hardness: Grade 2 / A307
Type: Carriage Bolt
Square-Depth: 3/16"
A carriage bolt has a domed or countersunk head, and the shank is topped by a short square section under the head. The square section grips into the part being fixed (typically wood), preventing the bolt from turning when the nut is tightened.
