uses Honey Brass, an alloy of copper and zinc, for crafting Coupling which is resistance to soft-water corrosion and hard-water calcification. Further the coupling has a ceramic top which is resistant to acid & other harsh chemicals.Stainless Steel Pop-Up Waste Coupling for Wash Basin ,Drain out let system 4 inch waste coupling is specially designed for your bathroom. Just shut off the coupling when not in use.. It is also an anti cockroach trap and and anti foul coupling.