5/16″-18 x 3″ Green Rinsed Zinc Grade 5 Carriage Bolts (72 pcs.)
Diameter: 5/16″ Length: 3″ Material: Steel Finish: Green Rinsed Zinc Head Style: Carriage Thread Size: 18 (Coarse) Thread Length: Full Hardness: Grade 5 Type: Carriage Bolt Box of 72. 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.