GM Genuine Parts Disc Brake Calipers are designed, engineered, and tested to rigorous standards, and are backed by General Motors. 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. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).