Pantographic Knives

A pantographic knife or (incorrectly) paratrooper knife is a folding knife whose blade is opened by a unique scissor’s method. The blade has a slightly longer tang than a folding knife heel. The handle is symmetrically segmented and articulated to fold away on both sides to grip the longer tang. The manner is similar to a butterfly knife (also called a Balisong knife after its modern place of origin) with which it is often confused. Unlike the balisong knife handles that swing freely and independently, the pantographic knife uses a pantograph linkage to keep the handles aligned during opening and closing. The pantographic knife is very strong when compared to most other folding knife designs, being joined at several points and along several planes, this increases the force required to break the blade away from the handle. By enclosing the blade on both sides, double edged blades can be used.
This knife is also known as a paratrooper knife, although it was never issued as such. The mechanism includes a collar that travels up the blade. This looks like an OTF gravity knife used by German paratroopers.