This type of spectacle was one of the most widely used, along with
nose-glasses (fi-tsu), at the beginning of the XX Century. Its shape is such
that the two lenses can be folded one on top of the other, held firmly by
a small hook, on the side of both lenses. The closing mechanism, as well
as that which maintains the glasses in their position, allows the flexible
bridge to remain firmly on the nose, utilizing the tension operated during
wear.
