When the nut is tightened or removed, the carriage bolt has a square shoulder under a rounded head that prevents it from rotating. They're useful for tightening wood-to-wood connections where the head isn't easily accessible. They can be used to build docks, swing sets, decks, and other surfaces that require a smooth finish.

Key Features

• Preventing the bolt from turning when the nut is tightened
• Square section grips into the part being fixed