Butterfly knife

The name "balisong" is derived from barangay (village) Balisong, part of the municipality of Taal, Batangas province, which along with the neighboring barangay Pandayan (now part of Poblacion zones 6, 9, and 10 of Taal town proper), were the original manufacturing centers of the knives in the Philippines.

Another claim is that balisong was originally an adaptation of a French measuring tool called the pied du roi ("foot of the king"), invented between the 1500s to the late 1760s.

In contrast, the French pied du roi was primarily a folding ruler, with the knife only included in some specimens as a novelty.

They were cumbersome to open and unlikely to be used for self-defense, especially since they also commonly included a metal tang at a right angle from the end of the handle to aid in measuring.

[9][10] There were also very similar designs to the balisong produced in England in the late 19th century, presumably also derived from the pied du roi.

In this handle, a groove is created (either by folding, milling, or being integrally cast) in which the blade rests when the knife is closed.

[13] Bearing-operated balisongs have small ball bearings housed in a circular concavity around the hole in the pivot.

Bushing-operated balisongs have a small metal bushing slightly thicker than the tang in each pivot hole with a usually bronze disc known as a washer on each side.

There are also washer-only operated balisongs which are usually much cheaper and lower quality than the other kinds, as they don't need bushings, but the handles will always bind to the tang when the screws are tightened enough and the washers, tang and handles all wear themselves down much faster due to the increased friction.

[14] The balisong has been outlawed in several countries, mainly due to its easy utility in crimes and its ability to be easily concealed for the same purpose.