Features: Aluminum alloy material, strong and durable. Convenient design and simple installation, easy to install on the bicycles with a locking threaded nut. Can be mounted to 27.2/28.6/30.4/30.8/30.9/31.6mm seatpost of mountain bike and other bicycles. Good finish and lightweight, taking no space and looks beautiful. According to the needs of your bike, there are five colors to choose from Specifications: Material: Aluminum Alloy Weight: 20g Size: As picture shows Type: 31.8mm/34.9mm Color: Black/Red/Blue/Golden/Colorful Note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x Seat Post Clamp