They are commonly used on docks and on playground equipment or in cases where it may be difficult to reach the bolt head with a tool.
The square shoulder on carriage bolts help to hold it in place while the nut is fastened. Carriage Bolts 3/8in-16 X 3-1/2in Grade 18-8 Stainless Steel 10PK Size: 3/8 inch-16 X 3-1/2 inchFeatures a smooth rounded head as opposed to a standard hex headSquare shoulder allows for nut to be tightened or loosened Often used in cases where a protruding bolt head could cause injuryNuts and washers not included, ensure washers and nuts are same diameterThread Type: Coarse, Thread Class: UNC-2A, Point Style: BluntSpecification(s) Met: ASME B18.