The Tecnifibre Ruff Code 1.25 tennis string has been developed with the use of Thermocore technology, which offers a more elastic polyester core in conjunction with the reduction of shocks & vibrations. A gear shaped surface provides an increased spin potential & the Biphase process has maximized the durability of the string. The string has a diameter of 17L (1.25mm) & the set provides 12.2m (40ft), which enables you to re-string one racket.