Product Description Coarse thread, zinc plated steel. Pack of 25. 1/2-13 Coarse thread Zinc plated steel Hex nut 50 Pack. From the Manufacturer 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.