Monroe MA819 Max-Air Adjust Shock Absorber 1/2 inch Piston Rod: Hardened and precision ground rod for consistent performance and long service life All Weather Fluid: Contains special modifiers to reduce friction and ensure smooth rod reaction Full Displaced Valving: Better valving range on both the compression and extension cycles of the unit for a smooth comfortable ride Sintered Iron Piston: Stronger than traditional metals, enhances durability for long service life. Lubricated Air Sleeve: Reduces friction for longer service life Provides smoother operation during suspension movement