Size: 18cm I tried these on indoors for about 10 minutes, but I ended up not using them and they became too small. There are a few wrinkles. I will also include the spare socks marine shoes that I purchased. I will pack them simply and send them to you. Aqua shoes that allow you to walk powerfully even underwater. Non-slip! Difficult to come off even when entering the sea or river while wearing them! Protects your feet firmly from rocks, coral, glass fragments on the beach, etc.! Easy to walk on hot sand and rocks! Convenient and not bulky! Great for pools, river play, and marine sports! ■Material: Upper material/EVA, nylon Sole material/Synthetic rubber ■Features: Upper/Velcro strap design for easy on and off. Uses breathable and draining mesh material. Insole/Increased thickness for improved comfort.