According to Repel Sharks, LLC and Bob Millings this anklet will repel sharks. The theory being that if you wear this item a potential shark bite might be averted.
It is well known that magnets repel some species of sharks but as far as we know none of these studies have been done on much larger charismatic in shore species like Tigers and Hammerheads.
Back in 2007 and again in 2008 we field tested shark repelling magnets in a non scientific study at Isla Guadalupe, Mexico with white sharks.
The results were less then satisfactory, in fact the sharks took no notice of the magnets and proceeded to devour presented hang baits.
So much for the concept and white sharks at least.
Companies that promote shark repelling devices should be bound by industry set testing with multiple species prior to making claims about repelling sharks.
Magnets are no replacement for site knowledge, local conditions, and decisions to remove yourself from the water when sharks are present.