Genuine Mares stainless steel spring straps are the first with buckles created to adapt perfectly to Mares fins. A great upgrade to standard fin straps, these spring straps do not need to be adjusted for size and easily slip over the heel securely. Available in 3 sizes. Small straps fit XSmall or Small fins, Regular straps fit Medium, Regular or MedLarge fins, and Large straps fit Large, XLarge or Giant fins.