QS Products are made from 304-grade stainless steel, which has the highest resistance to corrosion, along with 316 and 316L.
The staining character and pit density difference between 304 and 316 are negligible and do not justify the 20 - 30 percent price difference.
PVD is a process where metal surfaces such as brass door handles and letter plates are placed inside a vacuum chamber and coated in a thin layer of molecules of hard wearing metals such as Zirconium. This layer of hard wearing molecules is so strong it stops the brass from tarnishing.
Black Powder Coated
Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or with ultraviolet light.