Polypropylene Grey has been enhanced with special heat stabilizers to increase the life of the material. This was first used in tanks and coatings for the chemical and semi-conductive industries. Along with the inherent properties of resistance. corrosion, this product can last for more than 50 years, comparing with the standard values of natural Polypropylene that has a life time of only 5 to 10 years in the same applications. Even at normal working temperatures, Polypropylene Gray. highly recommended. The small cost difference, compared to lower quality products, is more than compensatory due to the considerable increase in the life of this product.