The open heel design is one that was originally designated as a cold water style which required the use of additional footwear in order to be used. The design of the foot pocket included an adjustable strap which allows for a more customised fit.Wearing this kind of snorkel fins, wet suit boots, water shoes or neoprene socks is required.Though known as cold water fins, these are also suitable for warm water use as well, but appropriate footwear is needed.