Flex Power Nano Tec Z Speed Badminton Racket (4U) Isomectric 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 Grommets system - This single-pass grommet holes construction provides more grommet holes, creating a high-performance stringing pattern that puts 7% more durability. Carbon Nanotube - The Carbon Nanotube is adopted in both sides of the frame in order to give strength and perseverance. It holds large amount of energy at the impact, and releases it back like an arrow. It gives you depth and control in your game. Whip-Slim Frame - The Whip-Slim Frame provides smaller flat surface compared with an ordinary racket for better speed, fast swing-through and the quicker maneuverability. 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 35lbs.