Our Post-Lock is a bicycle rack attachment point that can be positioned anywhere on your seatpost to provide a mounting point. Post-Locks do not have a lip like our Lip-Lock, Flip-Lock, and Rack-Lock so therefore cannot be used as a seatpost clamp. - NOTE: This IS NOT a seat collar and CANNOT BE USED to keep your seatpost in place - NOTE: NOT FOR USE with carbon fiber seatposts - NOTE: Please consult your seatpost manufacturer to check compatibility - Max torque 3-5Nm - AL-6061 Aluminum - Strong rack attachment points - 34mm-wide rack mount threaded for M5 bolts - Available for 27.2, 30.9, and 31.6 mm diameter seatposts