Real vintage monocles were custom-made for the original owner. A cast was made of the bone structure between the eyebrow, cheek, and nose. This cast was used to create a mold to form a gallery. The gallery served to keep the monocle in place without deforming the face and also to extend the lens forward to make room for the eyelash. A properly fitted monocle did not fall out and was not uncomfortable to wear. The gallery can be reformed by a jeweler through heating and bending. However, the fit will never be as good as that of a monocle gallery formed by a mold. Monocles were expensive in their day. Relatively few were made and they are scarce today. This pair has a 40mm lens size. The lens can be changed to your own.