Specifications: Crafted from super sturdy carbon fiber and with firm construction. Allow to adjust the angle of your seat (Seat not included). If your seat already has a clamp, you can remove it and install our seatpost the same. Kindly note the insert the seatpost into your bike deeper to exceed the safety line. Thickened tube, hard to rupture. Five common methods for seat tube size selection: 1. Look at the original 1 seat tube on the frame, there will usually be a size mark, buy according to this mark, generally you can't go wrong 2. Commonly used data Measuring length = size (diameter) to be purchased 86mm=27.2mm 97mm=30.8mm 100mm=31.6mm 4. If the size is not marked, or if you buy a new frame, you can use a small piece of paper to circle the seat post and make a mark on the heavy box. 5. Use a ruler to measure the length and divide by the pi ratio π (3.1415926). For example, if the measured length is 86mm, then the diameter of the tube socket is 27.2mm, because the length is manually measured. When the calculated value is close to which specification in the table is that specification. Item Name: Bicycle Seat Post Material: Carbon Fiber Attributes: Type A: 27.2x350mm, Type B: 27.2x400mm, Type C: 30.8x350mm, Type D: 30.8x400mm, Type E: 31.6x350mm, Type F: 31.6x400mm Scope Of Application: Bicycles, Mountain Bikes Features: Durable, Stable, Easy to Use Size: Type A: Length: 350mm/13.78", Outer Diameter: 27.2mm/1.07" (Approx.) Type B: Length: 400mm/15.75", Outer Diameter: 27.2mm/1.07" (Approx.) Type C: Length: 350mm/13.78", Outer Diameter: 30.8mm/1.21" (Approx.) Type D: Length: 400mm/15.75", Outer Diameter: 30.8mm/1.21" (Approx.) Type E: Length: 350mm/13.78", Outer Diameter: 31.6mm/1.24" (Approx.) Type F: Length: 400mm/15.75", Outer Diameter: 31.6mm/1.24" (Approx.) Notes: Please be sure to figure out the outer diameter of the seat tube of your car when buying, so as to avoid buying it back and not using it. 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. Package Includes: 1 x Bicycle Seat Post 1 x Screw 1 x Gasket 1 x Lower Gasket 1 x Connector