Backing plate. Left.DISC BRAKES. Rear. Right.DISC BRAKES. W/SIERRA C3 OR DENALI. A Backing Plates used on a drum brake braking system, used to contain brake shoe dust, as well as protect the brake drum components from water, dirt and debris. A Shield used to contain the brake dust produced by the brake pads of a vehicle's disc brake calipers. This typically is mounted to the vehicle's wheel hub. Additionally, it functions as a splash guard to protect a vehicle's disc brake rotors from water, dirt and debris. Parking Brake. cover. Brake Dust. Brake Splash Guard. Caliper.