ACDelco Gold (Professional) Friction Ready Non-Coated Disc Brake Caliper s are a high quality alternative to Original Equipment (OE) parts. Disc Brake Calipers are hydraulic components mounted over the brake rotor. The caliper acts as a clamp to press the brake pads against the brake rotor when the brakes are applied. ACDelco Gold (Professional) parts are manufactured to meet your expectations for fit, form, and function, making them a smart choice for General Motors vehicles, as well as most makes and models, including special applications. These high-quality parts are backed by General Motors. Some ACDelco Gold parts may have formerly appeared as ACDelco Professional.