... steel, stainless steelSurface treatmentZinc, colour zinc ,nickel, ect..And it can be made environmentally friendly.SizeNon-standard, so you ... screw, a spring washer, a square washerFunctionAnti-loose and buffering1.Product Profile Pan head electronic combination screw fastener ... for nearly then years, and we win a good reputation for our quality and after-sale service. We always persist in ...