We have a friend that got sea sick all the time. We gave her ginger cookies and the wrist bands and she managed 10 days in the Virgin Islands, 25 plus winds and at times I even took her into the Atlantic 10 foot seas. She never got sea sick until we put her on land at Cruz Bay. Forgot to tell her she would still feel like she was on the boat. She didn''t get over it until she was back on board...:-))
Don''t know but they did work for her. Practical Sailor did an article a few months back. They tried the expensive automatic one and said they would recommend it highly.