The tecnifibre duramix hd 135 tennis string has a multifilament construction and a silicon pyrogene lubritec additive that reduces elongation and improves durability by up to 40 multifilaments have been reinforced with polyester to provide the user with high quality product that offers comfort and top performance the string has a gauge of 15l 135mm and the set of it provides 40ft 122m which is enough to re string one racket