Left.FWD. Right.FWD. A cover, typically made of plastic or rubber, which protect the disc brake caliper guide Pin heads from dirt, debris and moisture, to prevent corrosion. A rubber boot used to protect the disc brake caliper guide Pin from dirt, debris and moisture to prevent corrosion. Disc Brake Bushing. Disc Brake Bushing. Disc Brake Caliper Slide Boot. Disc Brake Caliper Slide Cover. Guide cap. Included with: Hardware kit.