Monroe MA829 Max-Air Air Shock Absorber 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 1/2" Diameter Piston Rod - Hardened and precision ground rod for consistent performance and long service life