When driven into the wood, the barbs prevent their working back out. Will not chip or break. Also used to tighten ladder rungs. Plated to resist rust. No. 8002: Size: 2, 5/8'' L. x 3/8'' W., 1/8'' thick No. 8004: Size: 4, 13/16'' L. x 7/16'' W., 5/32'' thick No. 8005: Size: 5, 1-1/16'' L. x 1/2'' W., 5/32'' thick No. 8010: Size: 10, 1-1/16'' L. x 15/16'' W., 5/32'' thick No. 8015: Size: 15, 1-1/4'' L. x 1-5/16'' W., 3/16'' thick