SCUBAPRO's JET FIN is famous. You may need help when sizing - call us we are experts in this area. Generally a Man who wears a size 10 or 11 USA sneaker would be a Large in most dive fins- Not trye for jet fins - if you wear a thin scuba diving boot you may be an XL or with 5  to 7 MM neoprene boots you will be XXL -  the XXXL size is more for very large feet with heavy Drysuit boots Tech divers, deep divers, military divers, commercial divers and dive instructors, as well as old-school recreational divers, still strap on a pair of JET FINS before hitting the water. There are many imitations, but there is only one JET FIN.