This +20mm Rear Flat Mount Adapter is for running 160mm rotors on a 140mm frame. It could also work for putting a 140 rotor on a 120 frame, or a 180 rotor on a 160 frame, you get the idea. We don’t normally care that much about being ultra-light, but we did machine out a little hollow section, so this adapter only weighs 9 grams, so that’s cool.

This kit comes with the screws that hold the brake to the adapter, but you’ll still need to find the right length screws to mount the adapter to the frame. Since those can vary quite a bit in length depending on the frame, those are sold separately