Features 1、If your frame head tube has an inner diameter of 42‑52mm / 1.6‑2in (common on roads and high‑end mountains), and you want to use a 28.6mm / 1.1in ordinary straight tube front fork, or a standard cone tube 1.5in front fork, then this headset is what you are looking for 2、Use high‑quality rubber, add a layer of waterproof ring in the bowl cover, anti‑corrosion, waterproof and sand‑proof, so that the service life of the bowl set is longer. 3、Equipped with double bearing, it is smoother and easier to maintain than loose ball bearing, and the turning of the handlebar is light and smooth. 4、Using T6 heat‑treated high‑strength aluminum alloy material, CNC process processing, the weight is light and the strength will not decrease. 5、Diameter of the lower bowl is suitable for the frame with the inner diameter of the lower end of the head tube of 52mm / 2in. 6、Built-in oil seal, high-efficiency waterproof, prolong life, effectively avoid installation gap problems, and install in one step. 7、Open design, open bottom block, matching dual-purpose bottom block (optional), more convenient to use. Specification Item Type: Bike Headset Bottom Gear Material: Aluminum Alloy Weight: Approx. 116g / 4.1oz Specification: 41.8 x 28.6-52 x 30 or 39.8 (Specification: 1 1/8in + 1 1/2in) Suitable for: Frame Head Tube with Upper and Lower Inner Diameters of 41.8-52mm / 1.6-2in, Used with Ordinary 28.6mm / 1.1in Straight Tube Front Fork, or Standard 1.5in Tapered Tube Front Fork (You Can Choose the Corresponding Option According To The Matching Front Fork) Package List 1 x Bottom Gear 2 x Bearing 1 x Urgent Ring 1 x Bowl Cover 1 x Sunflower Screw Top Cover