Material: Stainless steel AISI 316.Treatment: two-factor Electropolishing.Axis: The axis of the hinges ROCA is a calibrated tube capped at both ends with two special trim to give a secure and resilient. The logo engraved on these rivets is your guarantee.The ROCA Pole Line Hardwares are unique electrolytically polished. Electropolishing is a procedure to shine, remove impurities from the metal and get an exceptional finish by removing a thin layer of its outer surface. Electropolishing has great benefits: It gives a high resistance to corrosion, including that caused by the potential difference of metals. Improves the look and achieves higher brightness, the disappearance of the micropores reduces risk of adhesion and low friction.