Suits for: Suitable for bicycles with a seat tube diameter of 31.8mm/ 1.25inch (Seat Post diameter is 27.2mm). Before purchasing, please confirm that your middle pipe diameter is 31.8mm/1.25 inch. You could measure the diameter of the seat pipe clamp that was removed from the your bike With Rear Rack installation holes: If you want to install a rear cargo rack on your bike, but the bike does not have rear rack installation holes, you could choose our product. It is not only a seat clamp, but also comes with a rear rack installation holes, so you can install a rear luggage rack on your bike Material: It's aluminium alloy material, the weight only 40g, sturdy and non rusting, lightweight, without adding to the weight of the bicycle Screw locking: Use tools to lock the screws tightly to better lock the saddle tube, so that the saddle tube will not slide and the seat will not move during cycling Packing including: 1 pcs seat clamp, 2 pcs screws(If there are screws on the rear rack, these two screws will not be used) WEEROCK Bike Seat Clamp 31.8mm/ 1.25 inch with Installation Holes for Bicycle Rear Rack Bike Cargo Rack Aluminium Alloy Seat Post Clamps. Sliver