IST FP01 Sumi Open Heel FinsSumi was designed with propulsion efficiency in mind. Utilizing different materials’ flexibilities and structural improvements such as water channelling guides on the blade and the 22º blade-to-foot angle, IST is able to create fins that are not hard on the legs yet generous forwarding force will always be provided. The fin’s foot pocket is also the product of IST’s time-consuming research and manufacturing experience. This is an often-neglected criterion when divers choose their fins and the we are confident that SUMi will be one of the most comfortable fins that people put on.Sizing (when worn with a 5mm boot): Small fits Men's 6-7 / Women's 7-8Medium fits Men's 8-9 / Women's 9-10Large fits Men's 10-11 / Women's 11-12X-Large fits Men's 12-13 / Women's 13+
