Depending on what size rotor you use, and what your frame/fork mount is, you will need a brake adapter to properly space your disc brake caliper. Rainbow mounting hardware included.

For example, if your fork has a Post Mount 160mm, and you want to use a 200mm rotor, you would need a PM 40mm adapter.

There are two standards for disc brake mounts: IS: 51mm International Standard, PM: 74mm Post Mount