One kit attaches to almost any scuba fin DIR style .025 stainless springs Internal caveline to limit overstretching of springs Heavy-duty nylon tube webbing 3 styles of 316 stainless steel buckles included "Old School" buckles fit Turtle™ Power™ Frog™ Jet™ Twin Jet™ Rocket™ and others "Large Post" buckles fit most of today's modern fins "Small Post" buckles fit Atomic split fins Available Sizes: 8". . . . .FP-08 10". . . . .FP-10 12". . . . .FP-12