Spring Fin Strap with Quick-Release Buckles Scuba Dive - Pair Fits most modern open heel scuba dive fins with Quick-Releas Buckles Corrosion Resistant Stainless Steel spring with comfort Grip Puller Small - unstretched 12-1/2", max stretch 15-1/2" Medium - unstretched 13-1/2", max stretch 17-1/2" Large - unstretched 15", max stretch 21"