Unlike standard shingles, TruDefinition Duration STORM impact-resistant shingles feature patented WeatherGuard® Technology. The integrated polymeric backing material of the WeatherGuard Technology allows Duration STORM shingles to meet one of the industry’s highest ratings for impact resistance, UL 2218, Class 4. In some areas, homeowners may qualify for insurance premium discounts – check with your insurance carrier for details. These shingles also feature SureNail® Technology for high-performance durability and outstanding gripping power.