Slipstick CB680 2 Inch Floor Protecting Rubber Office Chair Caster Wheels (Set of 5) Standard Stem Size - Black/Gray Rubber wheels protect hardwood, laminate, tile, slate, and all other hard floor surfaces Features standard 7/16 inch (11mm) stem and easy-rolling 2" (50mm) twin caster rubber wheels Heavy-duty rubber caster wheels. Ideal for replacing existing office chair wheels and protect polished floor surfaces. High impact black polypropylene dust cover Eliminates the need for ugly expensive plastic floor mats.Note: Wheels should be checked and cleaned periodically Each rubber caster wheel can support up to 66 lbs. Set of 5 holds 330 lbs maximum