The butterfly knife or bali song is a traditional knife design from the Philippines. They use a pair of rotating handles that function as the blade’s sheath when not in use. The blade styles can be single or double edged, depending on if the blade was meant for utility, defense, or aesthetics.
Butterfly knives can be easily opened with one hand and are restricted/illegal items depending on your location. They are commonly used for knife tricks or “flipping”, but it is recommended you practice with a blunt trainer before attempting any tricks. Check your local laws before purchase.