Sharkbanz Shark Deterrent Band are devices aimed at reducing risk when diving near predatory sharks thanks to strong magnets that don't require charging. Sharkbanz do this by temporarily interfering with their magneto-reception mechanism that sharks (and other fishes of the Elasmobranch Sub-Class) use to navigate. Footage of the these deterrents in the water shows their high level of efficacy especially in dirty water and close proximity.
The functional idea is that sharks can experience the same sensory-overload that humans can experience from loud music or bright lights. It seems simple, and chucking a big ol magnet in a waterproof watch housing is how they've done it, so really, it is quite simple.
Do sharks want to attack humans?
Short Answer: no, Long Answer: absolutely definitely not. Why? Sharks can lose a substantial number of teeth in an attack which can render them unable to hunt until their teeth have grown back. The problem arises when a shark looses it's teeth due to territorial-aggression or self-defence as it is now unable to hunt for sustenance, this is why sharks very rarely attack each other but opt for visual defence mechanisms, like looking big and scary (that's not a joke).
American research from the 80's has led us to believe that a Great White Shark (GWS) could be sustained for 6 weeks from 30kgs of mammal blubber but contemporary Australia research have found that this will sustain a GWS for 12-15 days. Mammal blubber is a type of adipose tissue (fat) that's basically a super-charged version of human fat. Sharks sense fat content through their teeth which is why there are countless videos of sharks teething on an outboard prop - outboard props emit electromagnetic radiation so the shark is simply trying to ascertain fat content, which is why humans are generally subject to a single bite: the shark realises we're not worth the teeth-loss.