Its ability to neutralise HCl during PVC production comes from its aluminosilicate structure, whose negative charge has been neutralised with sodium cations. The use of zeolites replaces lead in thermal stabilisers on the basis of calcium and zinc salts. With the use of zeolite in PVC stabilisers, the commitments of the European Stabiliser Producers Association (ESPA) and the Vinyl Plus programme have been successfully met. The uniform size distribution of zeolite crystals (d50 = 3–5 µm) means they can be homogeneously mixed in various formulations. High whiteness and the absence of visual impurities are the main properties of the Ultra-clean Zeolite ZP-4A-TSR. This is especially important in the production of PVC window profiles, pipes, insulation and other PVC products.