ACDelco 18A277 Professional Rear Disc Brake Rotor Assembly Rust-preventative coating provides corrosion protection for superior durability Inspected for balance; resulting in smooth brake operation and noise reduction Independently tested, including D3EA, along with Noise/Vibration/Harshness (NVH) and durability/wear testing; resulting in high quality and reliable products Follows original manufacturers' designs for dispersing heat, helping to prolong pad and rotor life while reducing noise and vibration