Description: 1. Office Chair Caster PU Robber Casters Safe For Hardwood Floors Carpets smoothness and Quietness small caster 50mm (2”) 5 years guarantee 2. Top Of Cover : Black PA6 / Wheel: Gray PA6 + Red PU(Polyurethane) 3. SGS OF ANSI / BIFMA CERTIFICATE 100,000 Cycles Pass ! 4. Background：more than 20 years OEM experience for NIKE and other famous sport brand