Description: 【Material】: The Adjustable Anti loose Quick Release Buckle Universal Fin Frog Shoe Heel Strap is made of TPR material, which is environmentally friendly, skin friendly, and resistant to aging. It remains flexible even in low temperatures. 【Convenient Design】: The quick release buckle design makes it easier to put on and take off your fins. It is very convenient to use 【Spring Straps】: These scuba fin straps feature springs that automatically tighten without the need for adjustment. They are simple in structure yet lightweight and . 【Feature】: Diving Fin Spring Heel Suitable for most open heel fins, such as for Cress, for Mares, but Not for Gull Coco fins. 【Package Includes】: Each package contains a pair of straps. Please 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. Specification: Material: TPR Size Chart: S: Spring length 27.2cm//10.71inch for shoe size 36 to 40 R: Spring length 29cm/11.42inch for shoe size 41 to 44 XL: Spring length 30.5cm/12.01inch for shoe size 45 to 47 Package Includes: 1 pair Diving Fin Spring Heel Note: Please allow slightly errors 1-2cm differences due to manual measurement.