This special vintage Wenger Esquire has a couple unique features. The most visible is the split nail file surface with the line down the middle. Another feature not that visible but probably more important is the scissors spring which is a coil spring hidden between the handles. It appears to be similar to many modern day spring assisted knives with a coil spring. The spring action is fairly weak but it works. The other feature is the unique way they made this knife with the blade springs stamped out of the steel liners. Look carefully at the last 2 photos to see this detail. Also there are a couple photos I took and posted over on SAKWicki many years ago here at this link and here. Wenger products are hard to date due to the factory fire but I feel this one is around the late '60s or early '70s.