Wilson's Duo Control 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 Wilson Duo Control Hybrid NXT 16 Tennis String | Christy Sports