This is a fantastic pair of “old school” Rubber Adjustable Fins, which feature: Excellent propulsion and comfort in a vented rubber design. The unique rubber compound allows you to achieve greater efficiency by reducing the overall weight. Power Vents reduce stress while accelerating water over the blade. Adjustable strap for a secure fit Easy adjust quick-release buckles.  The snapback quality and many years of reliability, makes this fin an unbeatable value!.