1.Our bolts is strong and durable. 2.China factory 3.Best price. 4.Good quality DIN 931 Hexagon head bolts ItemDescriptionNameDIN 931 Hexagon head boltsStandardDin, ISO, ASTM, BC, JS.MaterialCarbon steel, Stainless steel, Steel alloy, Aluminum alloy, Brass, Copper or customer's requirementSizeM4-M30Surface Treatment Plain, Cr, Black Cr, Ni, Gold, Black, Zinc plated, HDG, Dacrotized, etc. ...