Upholstery Metal Tack Strip is flexible, used to attach fabric in curved areas so that staples will not show. 3 Teeth Pattern provides extra gripping strength. Galvanized Metal. Choose length in the dropdown menu, 5, 10 or 25 feet. Most commonly used on arched outside backs, curved arms and outside wings on a wingback chair. Alice Ann’s tip: Flexible metal tack is sharp so be careful when handling. Wear gloves and keep band aids handy!!