Wilson's Duo Power is a hybrid string that blends NXT Control with Luxilon 4G Rough for a string bed optimized for spin, precision and tension maintenance. For ideal playability, reduce tension on Luxilon 4G Rough at least 10%. Either string can be installed in the mains for superior control and performance. Blend of NXT Control & Luxilon 4G Rough Ultimate control Reduce tension on Luxilon 4G Rough at least 10% for ideal playability Racket String Category: Hybrid, Control String Gauge: 16 L (1.25 mm), 16 G (1.32 mm) String Material Poly-Ether-Ether, PU String Type Hybrid