bolts nuts fasteners 1.material: steel,brass,stainless steel 2.finish:self color,zinc & clear, zinc & yellow,HDG We are one of the leading manufacturers of manhole covers, dismantling joints, rubber O-rings, steel flanges, fasteners, pumps, motor shells and other castings and forgings. Our products are made according to different standards, such as ISO2531, EN545, EN14525, ISO4422, ISO7005, ...