They have a version now for surfboards as well. The shield works by putting out an electromagnetic field that scrambles Shark Senses when they get close. The shield is not perfect, however. There has been at least one fatal attack on a diver who was wearing the device, perhaps improperly. Great Whites are known for suprise attacks where they build up an enormous head of steam, hitting speeds up to 20mph before barrelling into their target. With that much headway a small electromagnetic field is unliely to stop them in the last second or so of the attack. But it's better than nothing.
Agreed. I'd rather be hit by a shark going 20 mph, than hit AND BIT by a shark going 20 mph.
YMMV...