X-Fullerene. The new generation of X-Fullerene has four radial ribs which unite the carbon atoms into a unique soccer ball structure. The X-Fullerene features in the resin which bonds carbon fibres to creates a cross-link construction. This translates to a 5% increase in repulsion power and 15% greater stability. Isometric square head shape - Developed by Yonex, the Isometric Square Head Shape provides a 32% larger effective hitting area than a conventional racquet. Unlike an ordinary racquet, whose main and cross strings vary in length, the Isometric Square Head Shape equalises the length of main and cross strings in the string bed and enlarges the 'sweet spot' for more consistent shot accuracy - even on off-centre hits. The new lightweight Built-in T-Joint is made from an epoxy resin material that enhances your level of performance by increasing the stability of the shuttle on the string bed and through the air. The new Yonex single-pass grommet hole construction provides more grommet holes at the 2 & 10 o'clock position on the frame, creating a high performance stringing pattern that increases durability by 7%.