3 Sets of 17 G and 1 set of 16 G.  The #1 String for Spin Potential according to USRSA playtesting! Bringing even greater spin potential than its thicker version, Tourna Big Hitter Rough Blue 17 provides excellent performance at a moderate price. Using the same poly-poly ether composition as the original Big Hitter, this string features a significant textured surface to enhance ball bite and create even greater spin. One of the few strings to utilize aluminum fibers, Big Hitter Rough possesses surprising resiliency and power from a typically stiffer string construction. This string still places its primary concerns on durability, control, and additionally spin allowing players to swing freely from the baseline without fear. The German engineered string placed highly in tension maintenance and resistance to string movement. Due to the stiffness and good tension maintenance, it is recommended to string this one 5-10% lower than normal. So if you are a baseline player searching for a durable string to create tons of spin to place your powerful groundstrokes, give this one a try.  The thinner gauge of this string gives enhanced spin and feel.