The Dunlop Black Widow 1.26mm tennis string set is designed with serious players in mind. It has a gauge of 17 (1.26mm) & was inspired by one of the world's deadliest predators to deliver ultimate durability & unmatched power. The string set is 12m (39ft) long & features high tensile, monofilament premium polyester, as well as a heptagonal outer profile to generate more spin.