NPT COS-3 3" x 6" Tile Continental Subway Charcoal - With regard to the durability of the bisque and glaze, this material is suitable for: all vertical applications - residential and commercial, all interior wall, countertop and floor applications, fireplace surround, hearth and firebox, light commercial flooring applications, all exterior wall applications including building facades, swimming pools, fountains and outdoor kitchens, including regions that experience extreme weather conditions subject to the method of installation. Variations of shade are inherent characteristics of all kiln fired products. Material can be cleaned with any mild nonabrasive household cleaning product due to the chemical resistant nature of the glaze.