Shanghai Jinrui Norm Parts Supplies Co., Ltd. was built in 2001 which located in Baoshan District adjacent to the Bao Steel Group.Shanghai Jinrui is a fastener enterprise who owes a set of R & D,Website:http://www.chinajinrui.net, design, production and sales of high quality.Square head bolts is similar with hexagon head bolt, but this kind of bolt, square head bolt has larger surface force, commonly used in rough structure can also be used for parts with a T-shaped groove, in order to adjust the position of the bolt.Square head bolts are divided into a grade4.8 bolt, grade8.8 bolts, grade10.9 bolts, grade12.9 bolts depengding on the strength. According to the screw wire material ,it's dividedinto iron bolts and stainless steel bolts, stainless steel bolts have SUS304 stainless steel bolts, stainless steel, SUS201 bolts, stainless steel SUS316 bolts.