These types of bands are outside serrated, which keeps the inner surface of the band smooth, preventing any damage to the insulation when tightening the bands. The band width allows for increased contact surface with the cable, further minimizing the risk of damage. PE/RPE bands have E.D.F. approval. Their special design includes a flat profile head, allowing for use in tight spaces. RPE bands are expandable and intended for multiple uses. PE/RPE bands were specifically designed for use in the power industry, but are also used in many other fields, particularly in areas with limited space, such as tying hoses or cables in tight shafts or channels. Colored versions are used to secure covers in children's playrooms.