he warrants that if prestige for multi sport use synthetic turf proves to be defective in material or installation workmanship, resulting in premature wear or a tuft bind performance of less than 9 pounds/force, during normal and ordinary use of the product for the sporting activities set out below or for any other uses for which HPES gives its written authorization, within 8 years from the date of completion of installation for fields over 30,000 square feet.