Aeris Accel Fin for Scuba or Snorkeling Angled blade ensures the best angle of attack for each kicking stroke. Side rails and center channel direct thrust behind the diver for maximum propulsion. Vents at the base of the blade improve water flow down the length of the blade for greater efficiency. High-stretch heel strap is fully adjustable and easy to slip on and off. Foot pocket posts also accept standard quick-release buckle fin strap assemblies.