Carriage bolts are fully threaded and also known as shaker screen bolts. They have a low profile head with a square neck that resists turning when nut is tightened or removed. Used for wood-to-wood and wood-to-metal applications. A square neck keeps them from turning when tightening a nut. A smooth, round head provides a finished look. Zinc plated fasteners have good corrosion resistant qualities and are a good choice for indoor and industrial applications. Grade 2: tensile strength: up to 5/8" - 64,000 p.s.i. (min) 3/4" diameter up to 55,000 p.s.i. (min). No radial bar marking on head. Made from low carbon steel.