Silent and Trackless: The casters are made of orange polyurethane (PU) material, easy to roll and silent and trackless, better protecting the ground, and can be rolled on a variety of ground. These casters are suitable for both indoor and outdoor applications. Suitable for trolleys, carts, workbenches, tool boxes, machinery, cabinets, stands, furniture, shelves, and various places such as: workshops, garages, kitchens and offices, balconies, laundry rooms, utility rooms, schools, shops, etc