Efficient viscous-dynamic mechanism - A fluid-dynamic mechanism reduces energy losses by 30%, enabling seamless leg kick transfer and improved fin performance while swimming. Flexible support and fit - The 3-stage adjustment system precisely adapts to different instep measurements, delivering tailored support for optimal stability and comfort. Tool-free quick-change function - The innovative Fin Strap connection allows tool-free mounting and removal, so straps can be swapped quickly for uninterrupted use. Durable and reliable construction - Thoughtful material selection combines strength and resilience, ensuring long-lasting performance of the fin holder. Key attributes at a glance - Function: enhances propulsion efficiency and fin performance - Compatibility: 3-stage adjustability for varying foot instep sizes - Size: adjustable to fit a range of users - Material: high-strength, wear-resistant construction - Performance: measurable energy savings and reliable operation Use scenarios - Pool training: improves kick efficiency during regular lap swimming, reducing leg fatigue and increasing propulsion. - Open water or snorkeling: supports comfortable, secure fit across different fins; quick strap swaps keep sessions continuous. - Training camps or triathlons: tool-free strap changes enable fast gear adjustments between workouts or stages, minimizing downtime.