The set contains 4 swivel casters, two of which have brakes. The diameter of each roller is 38mm and the screw size is M8 x 20mm. Our casters are made of high-quality TPE material with good abrasion resistance. The wheel core is made of polypropylene, which is highly thermoplastic and corrosion-resistant. The outer wheel is made of synthetic rubber, which is wear-resistant and has good anti-slip effect. These casters run quietly and smoothly without scratching the floor. It can support up to 80kg and can be used for coffee tables, children's beds, cabinets, etc.