... than 20 years experience in special fastener 1,Name:Metal step ferrule;step ferrule;metal ferrule 2,For the similar ferrule,what ... ,5.6,6.8,8.8,9.8,10.9,12.9,etcCarbon steelGr.B,Gr.C,Gr.D,Gr.36 ... is machined hardware fastener ,especially the cutting/turning parts. Metal step ferrule