Polyurethane is mechanically bonded to a high density polypropylene core. This mechanical bond eliminates bond separation due to wet conditions. The combination of both materials provides for a long lasting, longwearing wheel that is impervious to water (including salt water), resistant to oils, grease, most solvents and chemicals. The UP wheel provides a smooth ride over rough surfaces. Urethane on Polypropylene Wheels are very popular, attractive, lightweight and extremely durable wheels used in countless applications. These polyurethane wheels are typically used in commercial, industrial and food service applications. The polyurethane tread is non-marking and offers a quiet ride, floor protection and excellent capacity ratings. These polyurethane wheels have a slight crown so that they maneuver very well. They are used in large numbers in the retail industry, shopping carts, platform trucks, etc. and can be washed down offering excellent sanitary applications.