This is a very early example of the model II, the release button has a more rounded shape, a type usually found on the fixed lens models.

The Stereoly first appeared in 1931 for the Leica I series. In 1932 a version suitable for the rangefinder model was produced, this used the same prism unit but had a different connecting arm.

There are minor differences between versions:

• The 1931 model came in two versions - rigid view-finder mask with a single positioning notch, later a folding finder mask was fitted and there were two positioning notches. With the connecting arm fitted to the camera the prism unit slides onto the arm and a spring engages the positioning notch.
• The 1932 model originally had two positioning notches on the arm to engage the 5 cm Elmar and the 5 cm Hektor. Shortly afterwards a third notch was added for the 5 cm Summar which was introduced in 1933.
• A version for the model IIIb was advertised in the 1939 US catalogue. This would have had a cut out for the IIIb eye-pieces which are closer together.

The stereo viewer, VOTRA, was a hand-held device which could also be fitted to a separately purchased stand (VOTIV). It has inter-ocular variation and independent adjustment to the eye-pieces. Leitz also sold binding strips (UMKLE) and glass plates (UGLYR) to make stereo slides.

An arm was separately sold allowing a Stereoly for a model I camera to fit onto rangefinder series cameras, this had the code VORUF.