PEI, the Porcelain Enamel Institute rating, is an abrasion resistance index used to determine the durability and resistance of ceramic tiles. The higher the PEI number, the more resistant the tile. Here are the different PEI rating classifications: PEI 1: For wall use only. Tiles in this class are not suitable for floors. PEI 2: For light traffic areas, such as bathrooms or bedrooms without direct access to the outside. PEI 3: For moderate traffic areas, such as kitchens, living rooms, or entryways without direct access to the outside. PEI 4: For heavy traffic areas, such as entrances, hallways, covered terraces, or light commercial spaces. PEI 5: For very heavy traffic areas, such as commercial spaces, airports, or shopping malls. ------------------------------------------------------------- The shade, also called the V value, is an index of the variation in both color and pattern that can be expected from a batch of tiles. Here are the different V value classifications: V1 (Very Low Variation): Minimal differences. The tiles are almost uniform with very little variation. V2 (Low Variation): Slight variations in color and pattern. The differences are noticeable but remain consistent. V3 (Moderate Variation): Significant variations. The differences in color and pattern are more pronounced, but each tile harmonizes with the others. V4 (High Variation): Strong variation in color and pattern. Each tile can be very different from the others, offering a unique and dynamic look.