Material The adjustable anti loose quick release buckle universal fin frog shoe heel strap is made of TPR and PVC materials. These materials are environmentally friendly and skin friendly, resistant to aging, and remain flexible even in low temperatures. Spring straps These scuba fin straps feature springs that automatically tighten without the need for adjustment. They are simple in structure yet lightweight and sturdy. Package includes Each package contains a pair of straps. Note that due to their larger size and weight, these straps may not be suitable for smaller or lighter fins where the size and weight may not be balanced. Quick release buckle The quick release buckle design makes it easy to put on and take off your fins swiftly and conveniently. Use scenarios Scuba diving or snorkeling with standard fins that use a frog shoe heel strap: the auto tightening springs provide a secure fit without fiddling with adjustments, and the quick release buckle allows fast entry and exit in and out of the water. Travel or rental situations: a paired set that fits a range of fins, enabling quick swaps between divers without tedious strap fiddling. Cold water or low temperature environments: the strap material remains flexible, helping maintain a reliable fit in challenging conditions.