Yonex Nanospeed Sigma Badminton Racket (NS-SIGMA) is a little headlight (even balanced) racket. This racket is for fast swing with power in mind. Structured with box frame the weight of the box frame helps generate more power similar to the NanoRay 700RP (Repulsion). The box frame also helps make the racket hold higher stringing tension. The NanoSpeed Sigma is recommended for intermediate players who want fast swing and power. onex NanoSpeed badminton racquets are Nano-powered by fullerene for more repulsion and speed from a compact swing. The YONEX nano-strucure uses nano-size particles of fullerene and carbon. The Yonex nano-particle engineering process gives YONEX sensitive control over how the badminton racquet materials function at the molecular level. It is a stronger headlight badminton racquet that delivers maximum power and speed from a compact swing.