About this item Fit steerer tube diameter: 1″, 25.4mm stems and forks.If you need 28.6mm(1-1/8 inch) Threadless Fork Tube Headset Spacer,Search ASIN: B08NYZ59R1 Material: Bicycle headset spacers are made of black anodized aluminum alloy material with smooth surface and exquisite workmanship, eco-friendly, sturdy and durable to use Comes Anodized in Black,Colorfast Surface,Ultra Precision Diamond Blade Machine Cut.Multi-size for You to Adjust The Appropriate Height Suitable of most Retro Steel Frame bikes,Commute bike ,Fixie bike,Kids Bike.durable to use.Perfect to get a good fit on your bike. Package includes:1 in Aluminum Stem Spacer *5pcs(10mm*4,5mm*1)