Upgrade the fit of your FoldingFins with stainless steel spring heel straps. 
The coil spring holds constant, even tension across your boot — a locked-in fit that won't loosen as neoprene compresses at depth, with no mid-dive adjusting. Saltwater-resistant. Sold as a pair.

Sizing: Shorter for boots EU 36–42 · Longer for EU 43–48. Pick by your boot size (cut varies by brand), not your foot.