Feature:1. The outer headset is made of aluminum alloy, made by T6 heat treatment and CNC process, with light weight and unchanged strength. Built in ditch ball bearing, efficient operation, lasting silence. Metal bearing 360 rotation, high accuracy, high speed, insert the fork accurately, unhindered and free.2. Integral sealed bearing, can effectively prolong the service life, the lubricant is retained in the bearing, dustproof and waterproof effect is good, suitable for harsh riding environment.3. Rubber waterproof circle, choose high quality rubber material, adding a layer of waterproof circle in the headset cover, anti corrosion, waterproof, silt prevention and durable.4. Suitable for frame head tube upper pipe inner diameter 44mm or 1.7in, the inner diameter of the lower pipe is 56mm or 2.2in, the upper outer diameter of the standard taper tube front fork is 28.6mm or 1.1in, the lower outer diameter is 39.8m or 1.6inm.5. Meanwhile, bicycle headset straight fork and taper fork general version, suitable the outer diameter of the upper end of the standard straight pipe front fork is 28.6mm or 1.1in and the outer diameter of the lower end is 30mm or 1.2in.Specification:Item Type: Bicycle HeadsetWeight: Approx.142g or 5.0ozMaterial: Aluminum AlloySpecifications: 44-56mm or 1.7-2.2in (General Purpose Version Of Straight Fork And Taper Fork)Applicability: The Inner Diameter Of The Upper Tube Of Frame Head Tube Is 44mm or 1.7in And The Inner Diameter Of The Lower Tube Is 56mm or 2.2in. The Upper Outer Diameter Of The Standard Taper Tube Front Fork Is 28.6mm or 1.1in, The Lower Outer Diameter Is 39.8m or 1.6inm. The Outer Diameter Of The Upper End Of The Standard Straight Pipe Front Fork Is 28.6mm or 1.1in And The Outer Diameter Of The Lower End Is 30mm or 1.2in.Applicable Measurement Instructions: (The Same Four Data Can Be Applied)The Inner Diameter Of The Upper Tube And The Inner Diameter Of The Lower Tube, To Obtain The Inner Diameter Of The Upper And Lower Tubes Of Frame The Outer Diameter Of The Upper End And The Outer Diameter Of The Lower End Are The Outer Diameters Of The Upper And Lower Ends Of The Front Fork..Package List:1 x Sunflower Top Cover Kit1 x Headset Cover1 x Urgent Loop1 x Upper Bearing1 x Upper Headset1 x Lower Headset1 x Lower Bearing1 x 30mm Bottom File1 x 39.8mm Bottom File