Description: This bike headset made of aluminum alloy material, which delivers good durability and stability. This product has high precision CNC machining and fine workmanship, which is anti-deformation and colorfast. This bike headset product is suitable for 34mm bike frame head tube and it is compatible for 28.6mm straight steerer fork. Easy to install use, which is a nice replacement part for your bike. Electroplating Surface: Internal sealed bearing with its surface electroplating polishig. The sealing ring is good for keeping dust and water away to prolong service life. Specification: Material: Aluminum Alloy Size Chart: Size: Applicable frame: upper inner diameter of head tube 44mm, lower inner diameter 44mm Applicable front fork: upper outer diameter 28.6mm, lower outer diameter 30mm, Applicable frame: upper inner diameter of head tube 44mm, lower inner diameter 44mm Applicable front fork: upper outer diameter 28.6mm, lower outer diameter 30mm, Applicable frame: upper inner diameter of head tube 44mm, lower inner diameter 50.6mm Applicable front fork: upper outer diameter 28.6mm, lower outer diameter 30mm, Applicable frame: upper inner diameter of head tube 44mm, lower inner diameter 50.6mm Applicable front fork: upper outer diameter 28.6mm, lower outer diameter 39.8mm, Applicable frame: upper inner diameter of head tube 44mm, lower inner diameter 56mm Applicable front fork: upper outer diameter 28.6mm, lower outer diameter 30mm, Applicable frame: upper inner diameter of head tube 44mm, lower inner diameter 56mm Applicable front fork: upper outer diameter 28.6mm, lower outer diameter 39.8mm Package Includes: 1 Piece Bike Headset