RXL SL Carbon Fiber Racing Bicycle Seatpost Clamp MTB/Road Bike Seat Post Clamps - 31.8mm for 27.2mm Seatpost - 34.9mm for 30.8/30.9/31.6mm Seatpost Material: Carbon Fiber+Aluminum screws Color:Black weight : About 20g Appearance: 3K Glossy Diameter:34.9mm length :15mm 34.9mm Fit for 30.8/30.9/31.6mm Seatpost