MADE OF GRADE 8 ALLOY STEEL: Corrosion resistance, good wear resistance, high hardness and high strength. 1/4-20, 5/16-18, 3/8-16 SAE SIZES: Size from 1/4-20 x1/2" to 1-1/2", 5/16-18 x 3/4" to 2", 3/8-16 x 3/4" to 2". Package includes 176pcs SAE hex bolts, 130PCS hex nut and130PCS spring washers. Total is 566PCS. UPGRADED STURDY PACKAGE: All the nuts and bolts and organized in a sturdy transparent box with size labels. This bolt assortment is heavy, we added foam protection around the box and a thickened kraft box. WIDE APPLICATIONS: The bolts and nuts kit are widely used in machinery, furniture, car and motorcycle repair and DIY design. GREEN PROTECTION: FOLIV is donating from this purchase to White Memorial Conservation Center Inc., which is providing year-round environmental education programs for children and adults to protect natural resources (i.e. vegetation, water, soil, and air). Hope we could do something for this beautiful green world.