The Nabaiji Swimming Training Fins Flippers are designed for optimal performance in the water. UK5.5/UK6.5 sizing for EU 39/40, these flippers are perfect for training and racing. Made with high-quality materials, these flippers provide excellent propulsion and maneuverability, making them a must-have for any serious swimmer. Whether you are a beginner looking to improve your technique or a seasoned athlete looking to enhance your speed, these flippers are sure to help you achieve your goals.