The Balisong is a folding knife also modernized as a "butterfly knife" or "batangas", with two handles counter-rotating around the tang such that, once closed, the blade is hidden among the handles.
Most notably called a Batangas knife, after the Tagalog province of Batangas in the Philippines, where it was traditionally founded. The Balisong was commonly used by Filipino people, especially those in the Tagalog region, as a self-defense and pocket utility knife. A stereotype used to exist that every Batangueño, or person who lives in Batangas, carried one everywhere he or she went. Hollow ground balisongs were also used as straight razors before conventional razors were available in the Philippines. Due to legislation, they are no longer as common in urban areas as they were in past decades. The name "butterfly knife" comes from its handles which open at both sides like the wings of a Butterfly to reveal the blade.
In the hands of a trained user, the knife blade can be brought to bear quickly using one hand. Manipulations, called "flipping" or "fanning", are performed for art or amusement. Balisongs are useful for situations where it is inconvenient to use both hands to open a knife. For example, a martial artist, who is using a single hand to hold on to something as protection whilst fighting, will not wish to use that hand to open a knife. In such a situation it is useful to have a knife that can be opened with either hand. They are also common in gangs as they can be easily concealed in most clothing.
The knife is illegal in many countries such as the Netherlands, Australia, the UK, Canada, New Zealand and Germany. In the Philippines, it is now generally illegal to carry one without identification or a proper permit in the streets of the capital because of their prevalent use in crimes and altercations. One now needs to demonstrate the need in professional livelihood or utilitarian purpose (such as cutting grass, preparing fruits and meats, being a vendor of knives, being martial arts instructors, etc.) to be able walk around with bladed implements in the urban areas. Another rule of thumb is that the blade of pocket knives must not exceed the length of the palm and must not be operable by one hand in order to be considered as a utility knife as opposed to a weapon (thus, Swiss Army Knives are legal).
- They were originally made from carved carabao and stag horn.
- A lone Batangueño, in a confrontation, fought off 29 assailants using one.
- They make"click clacks" from the sound they make when they are opened and closed.
- The traditional balisong is said to be called the "Veinte Y Nueve" because they are 29 centimeters long.
- Balisong knife trainers feature a unsharpened "blade", and are legal in areas where balisongs are not.