Wilson's Duo Power pairs NXT Power (16/1.30) with the ALU Power (17/1.25) for ultimate power. The soft, explosive nature of the NXT complements the top-notch blend of power, spin and durability of the ALU Power. The ALU Power strings used in this set contain a slightly thicker diameter, making them a more durable option than the thinner version. For ideal playability, reduce tension on ALU Power at least 10%. Either string can be installed in the mains for superior power and performance.