minus joint with double thread material:iron SGS audited More than 20 years experience ... ,12.9,etc Carbon steel Gr.B,Gr.C,Gr.D,Gr.36,Gr.58,1010,1015,1016,1020,1045,etc ... ,etc Ability for the surface finish: Electroplate Zinc plated(while,colour,dacroment),Nickel plated,copper plated,gold plated,chrome(3+Rohs ... so that you couldavoid lots of risks. minus joint with double thread