Diving fins 1. Fins with Whale's tall make more powerful thrust 2. Adjustable buckle 3. With different sizes Diving fins TF-F25011.Junior Size:S/M (US:9-13, EU:27-32),L/XL (US:1-4, EU:33-38)2. Adult Size:S/M (US:4.5-8.5, EU:9.5-10.5)L (US:38-40, EU:44-46)3. Fins with Whale's tall make more powerful thrust4. Adjustable buckle