I shall probably worry a few people who think that they know me at this point, but nothing new there.
In traditional oriental medicine there is a point called "Pericardium 5", which has nothing to do with your Pericardium, but is located in the centre of your wrist underside, the length of your end thumb joint below the top crease inside your wrist (nearest crease to the palm. If you prod that point with a finger tip, you'll feel that it's a bit more sensitive than the surrounding skin.
P5 as a pressure point will, if massaged, counter nauseum. These "anti-seasickness bands" (which you can buy in boots, most airport shops, etc.) have a sort of blunt stud which pushes into the point.
So, TCM (Traditional Chinese Medicine) tells you it will work. My experience is also that it works, but if you are just sat there in steerage, idly massaging that point with the thumb of your other hand, works much better than an inanimate band.
So, I'd suggest saving your fiver and do-it-yourself!
G
(Yes I do practice a variation on oriental medicine, but purely as a hobby. For the record, I practice Kempo and Shiatsu - the former a martial art, the latter healing - they complement each other well, both at a lowish but reasonably competent level.)