Keenso Bike Headset Bearings, 41.8?52mm M4/5 Mountain Road Bike Bearing Headset Straight Tapered Tube Parts Suitable For -- 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. Light and Smooth -- 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. Qualified Rubber Material -- Bearing Headset uses high‑quality rubber, add a layer of waterproof ring in the bowl cover, , waterproof and sand‑proof, so that the service life of the bowl set is longer. How to Use: 1. Choose the right headset according to the upper and lower inner diameters of the front frame head tube. 2. Coat the inner side of the head tube with grease for easy installation and disassembly, and maintenance while pressing in is more labor‑saving. 3. Assemble in order. It is recommended to press into one bowl first, and then press into the other one after completion, to ensure successful pressing. 4. Tighten the nut clockwise and press it in slowly. 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