... ,carbon steel 3.free sample 4.over 10 years maker black wood screwsFeatures:Material:stainless steel,carbon steelSurface:nickel plated, ... zinc plated,black zinc,color zinc black oxideGrade:4.8,6.8,8.8 ... JIS,BSW,ANSI,ISO & non-standard productsSurfacePlain, Yellow zinc, black phosphated, grey phosphated, nickel platingQualityBe affordable but of very ...