The Wolf Tooth Post to Flat Mount Brake Adapter allows flat mount brakes to be added to a frame or fork that was designed for post mount brakes. This is a vital component for cyclists who want to run a road groupset on a mountain bike frame. It is important to note that this is a +20mm adapter, which means a 140mm post mount native size will only work with a 160mm rotor, just as a 160mm post mount native size will only work with a 180mm rotor, and so on. Wolf Tooth Post to Flat Mount Brake Adapters are CNC machined from 6061-T6 aluminum.