The patent relates to a handle along the top of the viewer to adjust the hinged flap holding the mirror. Several variations of the viewer exist, some are mounted on stands, some have flush mounted lenses.

The lenses used in these viewers are generally two half-lenses reversed so that their thin edges are together. Some early models used quarters of a lens. On later models, after 1856, the lenses are often cut square and mounted flush with the front of the viewer. Large eye-pieces, either in wood or brass mounts, also date from around 1856.

The lenses create a virtual image at a comfortable viewing distance of the relatively close stereo images, the prism shape of the lenses converges the stereo images to the eye. On much later viewers, from the 1920s and 30s, which had small images whole lenses were used.