Most clear cases are made from TPU, and TPU oxidises — UV light, heat and the natural oils on your hands break the polymer down until the plastic itself turns yellow. It is a chemical change, which is why it cannot be cleaned off. Clarity is built from PCTG co-polyester instead, an engineering material that does not have that chemistry in it. It is not a treatment or a coating that wears off. We have also moulded a scratch-resistant layer into both faces of the back panel, inside and out, so it resists the internal hazing that makes clear cases look cloudy.