The Hexlox is a small stainless insert that fits into the already existing hex bolts, wherever you might have them screwed in. By inserting the Hexlox you block access to the hex bolt so any potential thief, equipped with a hex wrench, simply cannot unfasten the bolt and steal your parts.
The Hexlox is fastened and unfastened mechanically - with the Hexlox Key - but held in place magnetically. Hexlox can not be removed with a magnet, no matter how big or strong it is since the magnet inside the Hexlox is shielded in the "outside" direction - making the Hexlox magnetic only in the "inside" direction. That's how Hexlox cannot be removed with a magnet from the outside but still holds in place in the bolt.