Tecnifibre X-One Biphase 17 String Reel Composition: composite microfilament biphase process and polyurethane Gauge: 16g (1.30Mm) 17g (1.24Mm) Length: 660'(200m) Durability: 16g- 6.76 17G- 6.3. Playability: 16g- 8.71 17G- 8.6