Brass knuckles, as the name implies, are traditionally made of metal. They saw a lot of exposure in combat in the early part of the last century -- in both world wars -- and metal designs were tough and easy to produce. In many cases, they were actually attached to other weapons, like knives. They were a last resort for soldiers in a close-quarters battle.
Today, though, brass knuckles have changed. You can still find them on knives and in traditional stand-alone designs, but they have a more widespread appeal, thanks, in large part, to movies and video games. In fact, they have been made into jewelry, with one of the most popular designs simply being a set of brass knuckles on a thin chain to be worn around the neck.
In addition, all brass knuckles are not made out of metal. A lot of other hardened materials are used in modern designs. This still does include brass, but it also includes acrylic, steel and hardened plastics.
It is important to know about the changes in materials and designs because they can be a bit misleading. You may think you're not breaking the law because your brass knuckles are made of plastic, for instance, or because you wore them as a necklace and not as part of a knife or another weapon.
However, the sale and manufacture of brass knuckles is illegal in Florida, and the statute specifically says: "Any instrument or weapon of the kind usually known as metallic knuckles." This helps to account for the changes in designs and materials.
It is important for those who are facing criminal charges to know all of the legal options that they have.