These steel screws have corrosion-resistant finishes. Also known as lag bolts, they have a hex head for a secure grip with a wrench. They press threads into material for a tight, secure hold. To prevent splitting, drill a pilot hole slightly smaller than the screw. Length is measured from under the head.
Zinc-plated steel screws resist corrosion in wet environments.
Hot-dipped galvanized steel screws have a thick coating for better corrosion resistance than
| Screw Thread d | 4 | 5 | 6 | 7 | 8 | 10 | 12 | 16 | 20 | |
| ds | max | 4 | 5 | 6 | 7 | 8 | 10 | 12 | 16 | 20 |
| min | 3.52 | 4.52 | 5.52 | 6.42 | 7.42 | 9.42 | 11.3 | 15.3 | 19.3 | |
| k | Nominal Size | 2.8 | 3.5 | 4 | 5 | 5.5 | 7 | 8 | 10 | 13 |
| max | 3.1 | 3.88 | 4.38 | 5.38 | 5.88 | 7.45 | 8.45 | 10.45 | 13.9 | |
| min | 2.5 | 3.13 | 3.63 | 4.63 | 5.13 | 6.55 | 7.55 | 9.55 | 12.1 | |
| s | max=nominal size | 7 | 8 | 10 | 12 | 13 | 17 | 19 | 24 | 30 |
| min | 6.64 | 7.64 | 9.64 | 11.57 | 12.57 | 16.57 | 18.48 | 23.16 | 29.16 | |
| e | min | 7.5 | 8.63 | 10.89 | 13.07 | 14.2 | 18.72 | 20.88 | 26.17 | 32.95 |