Special Features Isometric head frame Equalizes the length of main and cross strings in the stringbed, enlarging the sweet-spot for more consistent accuracy even on off-center hits. 76 Grommet Systems This single-pass grommet holes construction provides more grommet holes, creating a high-performance stringing pattern that puts 7% more durability. Armor Speed Frame The lightweight frame and distinctive cross sectional shape at the top and side of the head reduce the racquet’s torque performance – improving both speed and control. Reinforced Structure Frame The new material is adopted in the frame in order to make the frame Ultra high Strength & Stiffness. As a result it can handle string tension of up to lbs.