A4. Boot kit. Left.W/QUATTRO. Right.W/QUATTRO. A rubber boot used to protect the disc brake Caliper guide pin from dirt, debris and moisture to prevent corrosion. Disc Brake Bushing. Exc.Vented Brake Rotors. Kit. cap. mount mount bolt. Disc Brake Guide Pin Boot. Disc Brake Slide Pin Boot. Included with: Carrier, Carrier assembly, Included with Carrier.