The Orca fins are designed to improve your kicking technique and ankle movement. They increase overall stamina and strengthen the muscles you use to kick, whilst helping to achieve a more natural and fluid movement in the water. Improve your kick and boost your performance. MATERIAL  100% silicone.  COMFORT  The fins can be adjusted to fit your feet perfectly, providing greater comfort whilst you swim.  VISIBILTY  The high-vis orange colour means you will be seen by your training companions, even whilst under water. SIZE Large is an EU 42.5 / UK 8.5