Very high durability premium steel with phosphate coated corrosion protection Ultra low and high performance friction ball cage mechanism High ball joint angles High performance design for loaded and unloaded units Dust bellows Original equipment quality retention ring Polychloroprene (CR) rubber dust blower (or equivalent material) Good mechanical strength High resistance to ozone and to high resistance to ozone and to the highest Good weather resistance to aging Low flammability Good resistance to chemicals and low temperatures