The EBC two-piece floating front rotor assembly for 2012–2016 Audi RS4 (B8) replaces OE floating SD-rotors with a serviceable two-piece design. EBC notes that switching to two-piece discs reduces unsprung rotational mass for sharper turn-in, better tyre contact, improved fuel economy and potential gains at the wheels; when the friction ring wears it can be replaced independently to lower long-term running costs.
EBC Racing 12-16 Audi RS4 (B8) Front Floating SD-Rotor Replacement Disc Rings (Pair)