Certified R-11 Anti-Slip Porcelain Floor Tile. Suitable for external use. PEI 5 for very high wear resistance….Snack Bars, Restaurants, Hotel Foyers etc. Scratch Resistance: 9 out of 10 on the Mohs scale. Grey tile with White speckles. Ideal in commercial areas or for domestic situations where slip-resistance is a concern. This is an extremely durable tile and is also suitable for exterior applications. Can be used on staircases in conjunction with its own matching bull-nosed step tile. All Houzz Tartan floor tiles comply with the A anti-slip bare foot requirements. Rocca Tiles recommend Tilemaster S1 Adhesive for this tile.