Based on cutting edge research (O'Connell et al, 2009, 2010 submitted), these anklets create a permanent magnetic field near your feet that is repellent to sharks. Good in low visibility water and where lemon sharks, southern stingrays, nurse sharks, and blacktip sharks are encountered. Male, female, and unisex styles are available. All feature non-corroding magnets, our exclusive magnet bushings (a total of six magnets per anklet!!), and clasps. Fit is adjustable using chain links. Watch a video of the anklet in action here (Youtube): http://www.youtube.com/watch?v=8BHd-AkSsJs