Injection-molded thermoplastic polyurethane tread with a nylon hub provides a durable wheel that is gentle on the ground. The track hardness is 98°Shore A, which is softer than nylon, but hard compared to molded polyurethane. Rolling resistance is slightly higher than for nylon. Suitable for use on smooth clean floors, where a quieter, more cushioned ride is desired than with hard nylon wheels. Resistant to oils, greases and many chemicals. TPU has higher resistance to metal chips, grit, etc. than rubber and nylon.