atomdoc office chair caster wheels, 3" newly lightweight caster wheels & revolutionary swivel vertical axle, safe protection for all floors including hardwood, set of 5 atomdoc <p>- brand-new design: revolutionary swivel vertical axle, bearing protection cover, blocking hairs, wools, etc. </p><p>- universal stem size: diameter 7/16"(11mm), length 7/8"(22mm), fit 99% office chairs. (exclude ikea’s)</p><p>- floor protection: polyurethane wheels protect all types of floors including hardwood, laminate, vinyl, tile, carpet.</p><p>- high quality material: strong high hardness 100% nylon bracket, high quality double ball bearings design, all-metal bearing rod.</p><p>- simple installation: just pull out the old casters and insert the new, pushing them in until they lock firmly into place, no tools needed.</p><p><b>package:</p></b><p>- set of 5 silicone wheels</p><p>- stem diameter: 7/16"(11mm)</p><p>- stem length: 7/8"(22mm)</p>