100 pack, 5/16-18, coarse thread, heat treated, zinc plated steel with yellow zinc dichromate finish, hex nut. .
Hex nuts are for general applications and are used with bolts and washers of the same finish. The most commonly used nut, they are often found in deck and fence building. The called out size is the inner diameter and the number of threads per inch or thread pitch. These nuts are left threaded.