Crown Molding Outside Corner: Made of virtually indestructible high-density urethane our corner blocks are cast from steel molds guaranteeing the highest quality on the market. High-precision steel molds provide a higher quality pattern consistency, design clarity & overall strength & durability. Lightweight they are easily installed with no special skills. Unlike plaster or wood urethane is resistant to cracking, warping or peeling. Factory-primed our corner blocks are ready for finishing.