... PackingCertificationRegarding to Bolts StandardDIN931,DIN933,DIN6914,ASTM A325M,ASTMA325, ASTM A-10,ASTM490M and other you would like to Grade4.8 ... so onSizeM6-M42 LengthM16-300Type of headSquare,Hex,Flange,Hex socket,T-Head and other you can chooseSurface treatmentBlack Oxide,Zinc ... 10years experience of manufacturing fasteners DIN125 M20 Flat Washer Grade A