√ All Floor Protection: Encased with soft, polyurethane material, protects hardwood, laminate, tile, slate, and all other hard floor surfaces √ Soft & Rolling Smooth: Fitted with dual precision ball bearings, no more dealing with chair caster wheels that creak and squeak with every roll. √ Heavy Duty: Stem，support bracketand internal parts are made of high grade steel, having the features of no distortion, long life. heavy duty design holds up to 660 lbs maximum.