Hillman 2154 Carriage Bolt with Nut (3/16" W x 4" L) Steel, Zinc-plated, Silver, 25-Pack Carriage bolts are designed to fasten a wooden face to either wood or metal. Flat, smooth head eliminates the need for a washer Square underside of the head is self-locking to eliminate the need for a driving tool Includes a nut for added security and stability Features a 10-24 Coarse thread type