5/8-11 X 3 1/2 CARRIAGE BOLT GRADE 5 YELLOW ZINC

A carriage bolt, also known as a coach bolt or round head square neck bolt, is a type of bolt designed with a distinctive domed or rounded head and a square section under the head. The square section prevents the bolt from turning when tightened, making it particularly suitable for applications where the bolted joint needs to remain secure while the nut is being tightened.

Carriage bolts are commonly used for wood-to-wood connections, such as attaching wooden components to one another or securing items to wooden structures. The square neck of the bolt fits into a square hole in the wood, preventing the bolt from spinning as the nut is tightened on the other side.