Wilson's Duo Feel is a hybrid string that blends NXT with Luxilon Element for excellent shock absorption and less string bed vibration. For ideal playability, reducing tension on Luxilon Element at least 10%. Either string can be installed in the mains for superior feel and performance. FEATURES: Blend of NXT & Luxilon Element Ultimate touch and feel Reduce tension on Luxilon Element at least 10% for ideal playability MATERIAL: Polymer, PU COLOR: Bronze Wilson Tennis String WRZ949730