HEAD Snorkeling Swim Fins, Blue, Large/Size 10-13 Features patented OPB hinge technology for a comfortable and easy kicking motion Channel-thrust delivers optimum performance with a minimal amount of effort Soft elastic heel straps attach using the quick-release buckle system, giving you easy one-time adjustment and allowing you to easily put on and remove the fins Power-and-efficiency in one-fin Construction: Tecralene and thermoplastic rubber