Chrome plated Scalloped billet aluminum outer cover. Engineered and proven to give your engine maximum airflow for more horsepower & torque. The patented hidden breather backing plate is O-ringed at the heads and exits inside the mouth of the throttle body for a virtually closed loop system; eliminating the need for any external hoses or hardware. - With Stage 2 cover - Increases horsepower & torque - 20% larger filter element than Stage 1 - Patented hidden breather technology - Pre-oiled high performance cotton gauze filter element - One-piece aluminum backing plate - Radius air inlet for unobstructed airflow - See 959660 for the replacement air filter element only