The set includes 4 swivel casters, two of which have brakes. The diameter of each caster is 38 mm, and the screw size is M8 x 20 mm. 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 properties. These casters roll quietly and smoothly without scratching the floor. They can support up to 80 kg and can be used for coffee tables, cribs, wardrobes, etc.