The Hillman 1/2 In. x 3 In. Grade 2 Zinc-Plated Steel Carriage Bolt is an essential fastener designed for securely fastening wooden faces to both wood and metal frames. With its innovative design, this carriage bolt features a flat head that eliminates the need for a washer, providing a sleek, semi-flush finish for your projects. The square underside of the head is self-locking, preventing any spinning during installation and eliminating the need for a driving tool. The zinc plating not only enhances the aesthetic appeal of the bolt but also offers rust resistance, making it suitable for various applications, although it may not be ideal for all exterior projects.