Disc brake caliper adapters to change rotor size for Magura disc brake calipers or to use (PM) 74mm calipers on (IS) 51mm frame or forks (FM) 70mm: Flat Mount fork 70mm (FM) 34mm: Flat Mount rear 34mm (IS): International Standard 51mm (fork commonly being160mm and rear frame mount to 140mm spec) (PM): Post Mount 74mm