PEI rating indicates tile hardness and is a guide to purpose and application of the tile. Class 0 – No foot traffic; Wall use only. Class 1 – Very light traffic in bare feet (i.e. bathroom); Interior wall use. Class 2 - Light traffic in slippers or soft-soled shoes (i.e. bedrooms). Class 3 - Light to moderate traffic; Any residential area or light commercial areas (i.e. offices). Class 4 - Moderate to heavy traffic; Medium commercial and light institutional use (i.e. restaurants, hotels). Class 5 - Heavy Traffic: All residential, commercial, and institutional floors.