Apollo Bio-Fin C-Series Open Heel Spring Strap Scuba Fins The only split-fin with built-in commercial grade strap Apollo's split fin design is consistantly rated as the fasted fin in the water providing exellent manueverability and position control Strap automatically adjusts to changing conditions; no stopping to tighten down a loose strap Durable stainless steel coil spring will not rust or break Rugged rubber grip with finger loop is easy to access, even with thick gloves