Brake adapter - Post to post
Post-to-Post brake adapters are for mounting Post type disc calipers to Post type frames/forks. The adapters come in both +20mm and +43mm sizes.
Are you increasing your rotor from 160mm to 180mm? Get a +20mm adapter. How about increasing your rotor from 160mm to 203mm? Get a +43mm adapter. Yes, it's that simple!