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. - Please 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 - Fits on post mount native sizes 140, 160, and 180mm - Works with rotor sizes 160, 180, and 200mm - Tested with SRAM and Shimano brakes - Requires minimum 13mm between top of brake boss to frame/fork - CNC Machined from 6061-T6 aluminum for strength and light weight - Includes : (2x) M5x13mm Flat Head bolts for Flat Mount Caliper and (2x) M6x15mm Socket Head bolts for Post Mount