The Alpine Astronomical Glasspath Corrector 1.25x is primarily intended to correct chromatic aberration and fringing that occur, especially on refractors, as a result of the additional prisms in binoviewers. The Glasspath Corrector is designed for use in the Maxbright and Mark V binoviewers to extend the telescope's focal point to improve your views and provide the ability to achieve tack-sharp focus.
This focal extending feature is what enables the use of a binocular viewer in most telescopes. When using a binoviewer, the distance incoming light must travel to get to your eye is increased, resulting in a lack of enough focus distance (back focus) to achieve proper focus. By using a compensator, the focal point of the telescope can be extended sufficiently to accommodate the length of the binoviewer.
In addition to providing critical back focus distance, the corrector adds 1.25x magnification in front of the binoviewer eyepieces. This Barlow-type function enables the use of longer focal length eyepieces to achieve high magnifications. These eyepieces tend to have longer eye relief than eyepieces with short focal lengths, so viewing is easier and more comfortable.