This is the advanced Rescue and Lifesaving fins. Including SpeedFins revolutinary Hyper footpockets for the best possible energy transfer and a new definition of swimming and diving. With a composite fiber - neoprene covered blade and a selection of blade width and stiffness Stereofins Hyper supply the divers and swimmer with unmatched power, speed and durability. The Fins blade is made from Hi-End and durable composite fiber to last for years. All SpeedFins monofins and fins blades are hand polished to ensure optimal streamline behavior underwater. Measurement Instruction: