Features: 1)diameter: M5-M20 2)length: 8-300mm 3)Material: low carbon steel, carbon steel, stainless steel 4)Grade: 4.8,8.8,GR.2/GR.5 5)Surface: Plain, Black, Zinc Cr+3,Yellow Zinc Cr+6,H.D.G.etc. 6)Packing: bulk, box packing, polybag