This is the ScubaPro Replacement PAIR Bungee Straps for Go Fin Features: Self-adjustable to ensure a versatile fit. Midi straps are designed to fit XS-S, M-L, XL and 2XL GO fins. Made of quality marine-grade bungee for years of reliable use. Available in 2 sizes - Mini and Midi. Mini is for fins sizes 3XS and 2XS; Midi is for fin sizes XS-XL. Sold in pairs. Replacement bungee heel strap allows for a versatile fit and makes donning and doffing the GO fin easy.