Unique 4-layer diamond bond pattern allows air and humidity to pass through the cover preventing paint deterioration and trapped air and moisture. Spun-bond polypropylene fabric has naturally water resistant fibers that shed water. (In extended rainstorms even the best fabrics will absorb varying amounts of moisture, but the IAP 4-layer cover dries easily and allows air to circulate thru the fibers. Soft and durable backing pamper paint finish and protects from sun, dust, dirt, moisture and pollution.