Butterfly knife

A balisong, also known as a butterfly knife, fan knife or Batangas knife, is a type of folding pocketknife that originated from the Philippines. Its distinct features are two handles counter-rotating around the tang such that, when closed, the blade is concealed within grooves in the handles. A latch sometimes holds the handles together, typically mounted on the one facing the cutting edge (the "bite handle"). An exceptionally large balisong is called a balisword. The balisong was commonly used by Filipinos, especially those in the Tagalog region, as self-defense and a pocket utility knife. Hollow-grind balisongs were also used as straight razors before conventional razors were made available in the Philippines. In the hands of a trained user, the knife blade can be brought out to bear quickly using one hand. Manipulations, called "flipping", are performed for art or amusement. Blunt "trainer" versions of these knives are also available and can be used to practice tricks without the risk of injury. The knife is either illegal, or the length of the blade is restricted in some countries. Often restricted under the same laws and reasons as switchblades or concealed weapons, additionally having restrictions in some countries due to the balisong being classified as a gravity knife. Within the Philippines, it is no longer as common in urban areas as in the past.