25 pack, 1/2" x 4" galvanized carriage bolts, designed to fasten a wooden face to either a wood or metal frame, its flat head is designed to eliminate the need for a washer & provide a semi-flush finish to applications, the square underside of the head is self-locking to eliminate spinning & the need for a driving tool, the galvanized finish provides optimal rust prevention but can be chalky in appearance.