Knuckle automatic knives, also known as "brass knuckle knives" or "knuckle duster knives," are a type of automatic knife that includes a set of brass knuckles as part of the handle. These knives are designed to be used as a self-defense tool, and the brass knuckles can provide additional impact and protection to the user's hand when used in combination with the knife blade.
It's important to note that while knuckle automatic knives may be legal in some jurisdictions, they are illegal in many areas due to their association with criminal activity and their potential to be used as a dangerous weapon. It's important to check your local laws and regulations before purchasing or owning a knuckle automatic knife.