6mm-1.0 x 40mm Zinc Plated Class 8.8 Steel Coarse Thread Carriage Bolts 8PK, Midwest Fastener, Mfr#: 31166

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.