Weight / Grip Size 4U / G6 Balance Head Heavy Frame Graphite+Nano Resin+Fiber Reinforced System Shaft Graphite+Nano Resin+6.8 SHAFT Stiffness Medium String Tension ≦35 lbs (16kg) POWER BOX The box-shaped design effectively increases the stability and anti-torque, can stand higher string tension. SEVEN SIX 76 The single-pass grommet hole construction creates less friction between strings, this effectively reduces tension loss, while extending string life. FRS Based on the design of multi-layered carbon fiber, the advanced Fiber Reinforced System (FRS) can not only improve the elasticity, but also offer stable controllability with high tension string. FREE CORE Designed by computer simulation and aided with the adoption of injection moulding technique, this revolutionized handle style allows the shaft to move more freely, which can not only make swings smoother but also improve overall handling experience.