Bike type:Mountain Bike Material type:Aluminium welcome to my store , Hope you have a pleasant shopping trip! Feature:1. How to Choose the Size:1.Check the Diameter of the Original Seatpost,choose the same Size as the Original Diameter.2.Measure the Inside Diameter of the Frame Tube.2. Application: 30.9mm diameter frame. 375mm is the external brake cable, and 400mm is the internal brake cable. Purchase according to your bicycle model.3. Function: You can adjust the height of the saddle according to your height. The height of the saddle can be adjusted with a length of 10cm to avoid the soreness of the back and shoulders caused by the riding posture.4.100mm Seatpost Internal/External Cable Routing Bike Seat Tube for Bicycle Mountain Bike Road Bike MTBSpecification:Material: 7075 aluminum alloyWeight: 653/628gSize: 37.5/40cmColour: BlackPacking list:1X Bike Seat TubeNotes:1. Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the pictures.2. Please allow 1-2cm slight dimension difference due to different manual measurement. About this item Use 7075 Aluminum Alloy to Make. Light Weight and Heavy Load.Purchase According to Your Bicycle Model. Function: You Can Adjust the Height of the Saddle According to Your Height. The Height of the Saddle Can Be Adjusted With A Length of 10cm to Avoid the Soreness of the Back and Shoulders Caused By the Riding Posture. How to Choose the Size:1.Check the Diameter of the Original Seatpost,choose the same Size as the Original Diameter.2.Measure the Inside Diameter of the Frame Tube. Application: 30.9mm Diameter Frame. 375mm Is the External Brake Cable, and 400mm Is the Internal Brake Cable.Purchase according to your bicycle model. SHOP WITH CONFIDENCE: To Provide You With the Highest Quality Service, If You Have Any Question, Please Feel Free to Contact Us.We Will Provide After-sales Service Until You Are Satisfied. Use 7075 Aluminum Alloy to Make. Light Weight and Heavy Load.Purchase According to Your Bicycle Model. Function: You Can Adjust the Height of the Saddle According to Your Height. The Height of the Saddle Can Be Adjusted With A Length of 10cm to Avoid the Soreness of the Back and Shoulders Caused By the Riding Posture. How to Choose the Size:1.Check the Diameter of the Original Seatpost,choose the same Size as the Original Diameter.2.Measure the Inside Diameter of the Frame Tube. Application: 30.9mm Diameter Frame. 375mm Is the External Brake Cable, and 400mm Is the Internal Brake Cable.Purchase according to your bicycle model. SHOP WITH CONFIDENCE: To Provide You With the Highest Quality Service, If You Have Any Question, Please Feel Free to Contact Us.We Will Provide After-sales Service Until You Are Satisfied.