Material: Aluminum Alloy Size: 1. 28.6mm is suitable for seatposts with an outer diameter of 25.4. 2. 31.8mm is suitable for seatposts with an outer diameter of 27.2/28.6 (some 27.2 seatposts use 29.4mm seat tube clamps, please determine by yourself). 3. 34.9mm is suitable for seatposts with an outer diameter of 30.4/30.8/30.9/31.6. Color: As shown in the figure Product features: 1. Quick Installation and Removal: With the quick release clamp design, you can easily install or remove the seat post, greatly facilitating your daily riding; 2. Wide Adaptability: There are three sizes of 28.6/31.8/34.9mm to choose from, which can meet the needs of seat posts of different specifications, and are suitable for multiple brands of bicycles and mountain bikes; 3. Easy Adjustment of Seat Height: The lightweight and easy-to-adjust mechanical structure allows you to accurately adjust the seat height at any time, making your riding more stable and comfortable; 4. Sturdy: Made of high-strength aluminum alloy, it has characteristics such as corrosion resistance and wear resistance, and can withstand the challenges of various extreme weather and road conditions; 5. Exquisite Appearance Design: The texture is delicate and smooth, and it matches perfectly with other accessories on your enhancing the overall aesthetic appearance. Package Includes: 1 pc Seat Post Clamp