The ultimate racing partner, the GX Sonic 6 CR, seamlessly blends compression and mobility. Sonic Line Design VI: New Sonic Line Design construction that is an update from GX Sonic V.  Gender specific design that better reflects the needs of elite, modern swimmers. The structure is different per model but, all aid in ease of movement and fast swimming. Sonic Light Ribtex UW II: Updated fabric from GX Sonic V.  Increased water repellency creating increased buoyancy. Flat Swim Technology: Enhances a swimmer's flat body line in the water.  Having a flat body line mimics streamline position, the fastest, most hydrodynamic swimmer's position.  Leading to low water resistance and good propulsion efficiency. World Aquatics Approved: Approved by World Aquatics for national and international swimming competitions. World Aquatics approved racing swimsuits have a unique FINA barcode printed on the swimsuit, making ti easily identifiable to swimming officials. GX-SONIC Series: Mizuno's most elite swim product, built for competition.