our products, hexagon socket head screw/collar head screw ranging from M5-M16 AND 1/4-3/4, are all made of top grade medium carbon steel and alloy steel with 4.8-10.9 intensive degree. Products for export are produced according to DIN, BS/ANS1 standard. While for domestic market, they conform to GB standard. Meanwhile, we also contract those projects of non-standard parts