HAIYAN BOLT produce this roofing bolt in carbon steel mostly. Product Description: Standard: French standard nfe25129,OEM,Customized GRADE: A307 GRA or 4.8 Material: carbon steel. Size:from 1/4" to 3/8", from 6mm to 10mm. Surface finish:zinc plated mostly Packing: cartons with plywood pallet Supply ability: 100tons per month Roofing bolt is …