1、Adopts metal bearings, 360° rotatable, high speed, accurately fit into the front fork, smoothly and freely. 2、Integral sealed bearing can prolong the service life. The integral sealed bearing keeps the lubricant in the bearing, which has good dustproof and waterproof effect. 3、Outer bowl is made of aluminum alloy, T6 heat treatment, CNC technology, internal full deep ditch ball bearings, efficient operation, lasting silent. 4、Choose rubber, add a layer of waterproof loop in the bowl cover, anticorrosion, waterproof and dustproof, longer service life. 5、Applicable to frame head tube, the inner diameter of the upper tube is 44mm, the inner diameter of the lower tube is 50.6mm, and the outer diameter of the upper end of the standard straight tube fork is 28.6mm and the outer diameter of the lower end is 30mm. Item Type: Bike Headsets Material: Aluminum Alloy Specification: 44-50.6mm (Use with 28.6 Standard Straight Tube Front Fork) Applicable Situation: Frame Head Tube: Upper Tube Inner Diameter 44mm, Lower Tube Inner Diameter 50.6mm. Front Fork: Upper End Outer Diameter 28.6mm, Lower End Outer Diameter 30mm. 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. 1 x Sunflower Top Cover Kit 1 x Headset Cover 1 x Urging Loop 1 x Upper Bearing 1 x Upper Headset 1 x Lower Headset 1 x Lower Bearing 1 x Bottom File<br> Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.