Poly II Poly wheels are injection co-molded from a black polypropylene tread molded and mechanically locked to a black polypropylene plastic core. Two-inch tread width wheels have a black tread and light gray core. Recommended for light to heavy loads on carpeted and hard surfaced floors. Poly II Poly wheels provide good floor protection, abrasion resistance, rolling ease, good impact strength and quiet operation. They are non-marking, are resistant to water, oil, and most acids and chemicals. Recommended operating temperature range is -20°F to 180°F. Poly II Poly wheels are available with a choice of plain, delrin, ball, or roller bearings. Available with optional black color decorative wheel hub caps. Special colors available in quantity. Tread Durometer: 60-75 Shore D.