[SAFE PROTECTION FOR All FLOORS]:These office chair caster wheels are encased with an extra-thick polyurethane layer and guaranteed not to scratch or leave marks on any surface even without using a chair mat. 100% safe gliding hardwood floor, parquet, laminate, linoleum, tile, short-pile carpet. (Not suggest using on the rug with over 2cm)[UNIVERSAL FIT(NOT FOR )]: Twin Ball Bearing casters office chair swivel wheels are designed with universal standard size rods 7/16 inch (11mm) x 7/8 inch (22mm) stem, heavy-duty design (a 5) can support up to 700 lbs. Can rotate on any rolling chair, whether it is a luxurious executive leather chairs or office chairs, computer chairs, game chairs.[SOFT & QUIET & ROLLING]: There twin wide transparent Twin Ball Bearing casters precision bearings and a shock-absorbing polyurethane tire can make the casters roll smoothly and on any surface without making any sharp sounds or noises.[VERY EASY TO INSTALL AND DURABLE]: Without any tools, pull out the old office chair casters and push in the new wheels to install successfully. At the same time, transparent polyurethane casters are more resistant to acid, grease, water and certain substances, so that the casters have a service life.size:Wheel diameter 50mmWheel width 55mmInstallation height 59mmInsert rod diameter 11mmHeight of plunger 22mmMaterial:PU polyurethane rubber metalcolour:Black+transparentPackage Contents:5 * Office Chair Casters WheelsOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.