The keystone is a popular addition to window surrounds. It also accentuates entryways and doors in both interior and exterior applications. The flat keystone adds a decorative touch to the home's most important architectural features. The keystone is basic and unadorned. It is crafted in urethane and designed for use with the moulding accent FLT159. The flat keystone is precision-molded and non-porous. The closed cell structure of urethane prevents the moisture absorption that can cause peeling, warping, staining and decay. Decorative urethane products continue to win favor for their affordability and enduring qualities. Now you can incorporate high performance and classic beauty into your decor with our urethane trim products.