CertainTeed No-Coat® Ultraflex 450 - 100' RollCertainTeed NO COAT Flexible Corner provides a perfect corner by fitting every angle, every time. Applied with joint compound, it has a uniform, strong, structural bond due to its paper backing. Faced with a tight fibered, high quality paperboard and backed with a joint tape paper, its ideal for applying paint or texture. NO COAT Flexible Corner 450 (4. 5") gives extra stiffness making it easier to work with runs longer than 10' (3 m), such as vaulted