Two rotor designs, two jobs. High-carbon rotors add carbon to the iron so the disc absorbs heat without cracking or ringing: that's the everyday upgrade over a plain cast rotor. Two-piece rotors bolt an iron friction ring to an aluminum hat, which cuts unsprung weight and lets the ring expand under heat instead of coning.
Both are engineered to HELLA's OE brake spec. Match rotor diameter and thickness to your vehicle before you order, and replace pads at the same time: new pads on scored rotors wear out fast.
