The Hillman Group 2152 10-24 x 2-1/2-Inch Carriage Bolt with Nut, 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