Ravenna Offset Umbrella Cover. The Ravenna Collection from Classic Accessories combines a striking style with durability, fade-resistance and convenient features. Zippered side makes covering and uncovering your umbrella easy. Double-stitched seams add strength and a stylish accent. Structured vents stay open to prevent wind lofting and mildew and are lined with mesh barriers. Laminate backing keeps your umbrella dry while elastic hem cords move easily through a special channel for a snug fit. One custom-colored buckle will keep your cover secure in any weather. Striped webbing adds an attractive accent and is unique to the Ravenna collection. Adjustable elastic hem cord slides easily and fits snugly for a tight fit.