This is a quality untarnished steel nylon insert lock in nut assortment that includes the most common sizes. This kit : 25pcs 6-32, 25pcs 8-32, 25pcs 10-24, 25pcs 10-32, 25pcs 1/4-20, 10pcs 5/16-18, 10pcs 3/8-16, 5pcs 1/2-13, 1pc Tuff Storage Container .