... 4.black,zinc plated,HDG,etc double end threaded rod 1.Features Material: Carbon steelFinished: PL, Zinc plated, HDG, Dacromet zinc, Black oxide, Nickel plated, Chrome plated, Cr+3, Brass plated Grade: 4.8-8.8 ... Standard: DIN, ANSI/ASME, BS, GB, JIS, Non-standard Diameter: M6-M39,1/4 ...