Features:Smooth and quiet ride-The 2.5 inch style wheels are great on hardwood, tile, and even carpet. All parts are made of high quality and ensure smooth maneuverability. Compatible with all top brands - 7/16" (11mm) x 7/8" (22mm) universal stem - Works with Herman Miller Aeron, Hon, Galam, Serta, Lane, humanscale Freedom, DXRacer and Steelcase gaming chair, Knoll ergonomic office chairs. First, measure your old circle. For installation-just pop out of the old wheels (you can grab them with a glove or towel) and push the new wheels. Bonus round – gives old chairs a new life. It gives the new chairs improved performance whisper quiet operation. Polyurethane Wheels Will Never Scratch Your Wooden FloorUpgrade your office chairs with our 2.5" style casters for office chair. Specifications:Material: PURshank Measurement: 11x2 2mm/0.43x0.87" Wheel Diameter: 63mm/2.48" (Approx.) Wheel Thickness: 2.4cm/0.94" Quantity: 1 PcNote: Please allow 1-3mm error due to manual measurement. Pls make sure you do not mind before you make a bid, due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!No retail packagePackage Included:1 x Rolling Caster