These commonly used plow bolts have a non-protruding head, and are used mostly in farming, construction, and in heavy equipment applications. These heavy-duty fasteners typically have a square neck to prevent the bolt from turning for added strength. The smooth bolt head surface means the washer would typically be placed on the bottom side, reinforcing the nut. Some plow bolts sizes come with nuts. Zoro also has a great selection of carriage bolts, freight car bolts, and elevator bolts too.