5/16″-18 x 8″ Zinc Grade 2 / A307 Carriage Bolts (67 pcs)
Diameter: 5/16″ Length: 8″ Material: Steel Finish: Zinc Head Style: Carriage Thread Size: 18 (Coarse) Thread Length: Partial Hardness: Grade 2 / A307 Type: Carriage Bolt Square-Depth: 3/16″ Box of 67. 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.