Headset -Bicycle Helmet Highlights Generic Brand Bicycle Helmet Description: This bicycle helmet is made of aluminum alloy material, which provides good durability and stability. This product features high-precision CNC digital machining and fine workmanship, which is anti-deformation and coloring. This bicycle headset product is suitable for 34mm bicycle frame head tube and compatible for 28.6mm straight steerer fork. Use easy to install, which is a nice replacement part for your bike. Electroplating surface: inner bearing sealed with its surface electroplating polishing. The sealing ring is good at keeping dust and water away to extend the service life. specification: Material: aluminum alloy Size chart: Size: Applicable frame: Upper inner diameter of the head tube 44mm, Lower inner diameter 44mm applicable Front fork: Upper outer diameter 28.6mm, Lower outer diameter 30mm, Applicable frame: Inner diameter upper head tube 44mm, lower inner diameter 44mm: upper outer diameter 28.6mm, lower outer diameter 30mm, applicable frame: upper head tube inner diameter 44mm, lower inner diameter 50.6mm Applicable front fork: upper outer diameter 28.6mm, Lower outer diameter 30mm, Applicable frame: Head Tube upper inner diameter 44mm, Lower inner diameter 50.6mm Applicable front fork: Upper outer diameter 28.6mm, Lower outer diameter 39.8mm, Applicable frame: Head inner diameter 44mm , lower inner diameter 56mm applicable Front fork: Upper outer diameter 28.6mm, Lower outer diameter 30mm, Applicable frame: Upper head tube inner diameter 44mm, Lower inner diameter 56mm Applicable Front fork: Upper outer diameter 28.6mm, Lower outer diameter 39.8 mm Package includes: 1 piece Cycling Helmet