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. Use hot dipped galvanized in outdoor applications and stainless steel in marine environments. Grade 5 fasteners are heat treated and are stronger than grade 2 fasteners. They are used by contractors, designers, OEMs, automotive repair and maintenance staff for critical joints and high stress applications. Tensile strength: up to 1" - 120,000 p.s.i. (min). Three radial bars head marking. Made from medium carbon steel.