These are the best quality on the market, directly from the manufacturer. All of our depth markers are screen printed onto the finest European frost-proof tile. They are then kiln-fired to over 1500 degrees to assure that the print is permanent. This process guarantees that they will never peel or fade. Our Silica abrasive is applied in our factory to the tile after printing but before kiln firing. This allows us to have the cleanest, crispest prints while maintaining the the highest standards of slip resistance. Our tiles have been tested by the Tile Council of North Americas Product Performance Testing Laboratory. The DCOF Accutest tests tile under both wet and dry conditions and passed with flying colors.