aFe Power's new differential covers bring performance engineering to the protection of your axle's differential. These differential covers are constructed out of durable cast aluminum with reinforced ribs for maximum strength. The covers come with all necessary hardware for easy installation. Pro Series differential covers include an oil level sight glass and magnetic deep reach fill plug. This cover is finished with black powder-coating and machined fins for a distinctive look. PRO Guard D2 Synthetic 75W-90 Gear Oil: The supplied gear oil exceeds the performance requirements of API GL-5 recommended for both open and limited slip applications. Increased Oil Capacity: The covers have increased oil capacity over stock for better performance over a longer duration. Built-in Internal/External Fins: Built-in internal and external fins transfer heat from the oil to the outside air for maximum cooling. Magnetic Plugs: This system incorporates a magnetic drain and deep reach fill plug to capture loose particles for maximum protection. Calibration Plug: Calibration plug set to the factory oil level to eliminate overfilling. Oil Level Sight Glass: A pre-installed oil level sight glass allows quick and easy oil inspection. When it comes to engineering for power, performance, protection and value, aFe Power is the only choice.