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: 1/2"
Thread: 13 TPI (Coarse)
Length: 12"
Thread Length: Partial
Material: Stainless Steel
Head Style: Carriage
Hardness: 18-8
Type: Carriage Bolt
Square-Depth: 9/32"
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.