minus joint with double thread material:iron SGS audited More than 20 years experience ... ,5.6,6.8,8.8,9.8,10.9,12.9,etc Carbon steel Gr.B,Gr.C,Gr.D ... surface finish: Electroplate Zinc plated(while,colour,dacroment),Nickel plated,copper plated,gold plated,chrome(3+Rohs &6+ ) plated,anodic oxidation ... so that you couldavoid lots of risks. minus joint with double thread