Features: A good replacement for your bike worn out or damaged headsets. These headsets ball bearings are designed for easy installation, allowing for quick and easily repairs. Make from steel, these headsets balls ensuring lasting performances for mountain bikes. Suitable for mountain bikes, kids bicycles, and stretch bicycles. Ensuring a smooth and comfortable ride for your bike. Specifications: Component: Steel Type: 01/02/03/04/05 01 Outer diameter: 20mm/0.79inch, inner diameter: 11mm/0.43inch, steel ball diameter: 5mm/0.20inch 02 Outer diameter: 25mm/0.98inch, inner diameter: 12mm/0.47inch, steel ball diameter: 6mm/0.24inch 03 Outer diameter: 29mm/1.14inch, inner diameter: 18mm/0.71inch, steel ball diameter: 6.35mm/0.25inch 04 Outer diameter: 37mm/1.46inch, inner diameter: 29mm/1.14inch, steel ball diameter: 4mm/0.16inch 05 Outer diameter: 40mm/1.57inch, inner diameter: 32mm/1.26inch, steel ball diameter: 4mm/0.16inch Package Includes: 4pcs Bicycles Ball Bearings note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.