The two lenses of the erecting system have diameters of 10 and 6 mm and focal lengths of 16 and 23 mm respectively; in front of the second lens, which is the one closer to the observer, there is a diaphragm with a 2 mm diameter hole at a distance of 5 mm.
The objective is protected by a hood surrounding the end of the tube which can slide on it to an extension of four cm.
The two telescopes are attached to a central axis around which they can be rotated, thus varying the distance between their optical axes from 5.5 to 7 cm; the observer can thus make the distance between the eyepieces the same as the distance between his/her pupils. The same axis is equipped with a screw that allows the user to move the two eyepieces simultaneously nearer to or farther from the objectives in order to focus.