The Tecnifibre 505 HPR string is designed exclusively for racketball & ensures maximum power & comfort. It is the official string of the International Racketball Tour & features a multifilament PU 400 inside. In addition, it incorporates the SPL (Silicon Pyrogene Lubritec) technology to reduce elongation & improve durability by 40%. The 505 HPR has a diameter of 17 (1.24mm) & comes in a 12m (40ft) set.