PREMIUM MATERIAL AND QUALITY: The caster is made of high quality polyurethane rubber, which makes it resistant to shocks and vibrations, reducing scratches and rolling noise. Exceptional flexibility and safety: the heavy-duty ball bearing system guarantees a freewheeling experience. The double locking system allows the non-slip wheels to be fixed on the sloping floor, which provides an additional guarantee of safety. Sturdy bearing: the solid stainless steel construction with a black paint finish makes it rustproof, no deformation or surface scratches. Each caster can support a weight of up to 100 pounds (4 per pack). Universal use: the wheels can be used in a wide variety of applications such as: flight cases, instrument boxes, display/exhibition equipment, transport carts, tool boxes, light machines, equipment carriers, mobile workstations, loudspeakers, cabinets, stands, amplifiers. , electrical cabinets, furniture, etc. 100% LIFETIME WARRANTY: If you have any problems with our products, please feel free to contact customer service, we will solve the problem in time. All feedback can help us improve and optimize our products.