The Vertex II Training fins have a short fishtail blade which helps to stabilize the ankles. The fin blades are constructed with a hard rubber material for increased propulsion. The fin's foot pocket is constructed with soft rubber for comfort and ease when putting on and taking off. The Vertex II Training Fins have sizes available from child size 8 to adult size 17.   SEE PICTURE FOR SIZES AND PLEASE SPECIFY WHEN ORDERING.