SIZE CHART: S-M(5-9): length 62cm, width 22.5cm, height 6.8cm, suitbale for shoes size 36-42; L-XL(9-13): length 67cm, width 25.5cm, height 7.5cm, suitbale for shoes size 43-46; XL-XXL(13-17): length 72cm, width 28.5cm, height 8.2cm, suitbale for shoes size 47-49. ADJUSTABLE STRAPS AND BUCKLESOpen heel design and adjustable straps make the swim fins suitable for different foot types and sizes, perfect to share with your friends and family, in addition it will let small pebbles and debris fall. The important part is the quick release buckle that keeps strap's length of the you have set, so you don't need to adjust the straps for every use, easy donning and doffing. PERFECT SWIM PARTNER Snorkel Fins with scientific design, minimize fatigue and prevent cramps, it uses the unique open toe and cool flame shaped mesh instep design, it will help to reduce resistance and you will feel more comfortable and breathable. It's can be used with water shoes and water socks (Reminder: Please purchase sizes up if wear with dive booties together). RELIABLE MATERIALThe foot pocket with TPE material+ PP material. That's anti-deformation, lightweight, corrosion resistant and durability. Sturdy and maintains flexibility. So it can fully achieve the comfort level of barefoot wear and don't worry about rubbing feet. Non-slip shadow design on the bottom, safe to use.