This is the Innovative Scuba Concepts Grip Tight Spring Fin Straps Features: Fit most fin styles with the rubber attachment knob molded into the fins Simply insert the solid cable wire into the knob holes and squeeze together with pliers. Sizing: Small 11" Medium 12" Large 13" XL 14" Experience a secure fit on every dive with Innovative Scuba Concepts&&';; Grip Tight Spring Fin Straps. Made from the highest quality materials, these straps feature a reliable spring-style closure for a snug fit that won&&';;t fail even in challenging conditions. Never worry about losing your fins underwater again. "