This Great Eastern Pattern #48 is my favorite Great Eastern Knife. It is slim, and slides easily in your pocket in spite of it's 3 7/8" length.
The Jack Knife is one of the oldest patterns in pocket knives. The origin of the knife is unknown because it is so old. We don't even know for sure where the name comes from. Traditional Jack Knives have two blades with both blades in one side and a bolster. The shape of the handle varies widely--from equal end to serpentine patterns like this one. The serpentine patterns are referred to as "Dogleg" Jacks.