... years experience 1,Name: Adjustable screw for sewing machine;adjustable screw;screw for sewing machine 2,For the similar screw,what can we do ... ?(1), Ability for the material of this ... kind of screw: Grade3.6,4.6,4.8,5.6,6.8,8.8,9.8,10 ... .9,12.9,etcCarbon steelGr.B,Gr.C,Gr.D ...