The Salsa Post-Lock is a bicycle rack attachment point that can be positioned anywhere on your seatpost to provide a mounting point. Extra useful for frames that have no upper rack mounts, or for better rack positioning. Post-Locks do not have a lip 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. NOT FOR USE with carbon fiber seatposts