Name: Bike frame mount headset Material: aluminum alloy Color: black red gold blue green purple Specifications: 44mm (suitable for 44mm inner diameter (about 50 outer diameter) head tube frame + 28. 6mm diameter front fork upper tube) Headset Features: Forged CNC machining shell, aluminum alloy material, anode coloring, laser marking, workmanship Very fine and light weight. Two stainless steel imported sealed bearings are used for the upper and lower sides, which are durable and easy to rotate Flexible, quiet and silent, high-end appearance Special Note: There is no general-purpose headset for the headset, and it cannot be installed if the caliber does not match Our headset Suitable for 44M inner diameter (outer diameter about 50) head tube frame (both upper and lower) (spinal tube frame and steel frame Not applicable )And it needs to be a front fork with 28.6MM outer diameter top tube (international standard) to use If you don't know the original caliber, please don't take pictures If you have any questions, you can consult customer service to avoid buying the wrong caliber and not being able to use it Cause unnecessary trouble About installation: Although the headset is a small part, the installation is more complicated, the most troublesome thing is the up and down The bowl needs to be pressed (professional tools) or knocked (it can be knocked with a rubber hammer, this method is simple, but there are also Risk, inexperienced use with caution