Aqua Sphere Size Chart The W-Challenger offers upgraded Yamamoto 39 neoprene throughout the entire suit for a comfortable race. Extend your reach with the Bio-Stretch Zone's unihibited range of motion. Features: - Bio-Stretch Zone: Strategically placed 2mm panels (under arms and lower back) that allow for maximum range of motion - 4mm Aqua Drive core body panel maximizes buoyancy and reduces drag - Thermo-Guard technology on chest, shoulders and legs to retain body heat - Quick-release ankle transition panels (horseshoe-cut design) for improved transition time - Easy-pull deep back zipper - Aqua-Flex collar seal to keep water out and prevent chaffing and restriction - Super stretch, SCS-Coated Yamamoto 39 Neoprene for ultimate comfort - 100% UV protection