Optical design of a simple device to simultaneously record spectra with 180 degree orientation. The design is optimized for the UVES spectrograph. The rays with different colors do not represent different wavelengths, rather the geometrical position of the extremes, to show visually how the green ray, which is located at the upper limit at the entrance, and the blue ray, which is located at the lower extreme, maintain the geometry in slit 1 while they are geometrically rotated in slit 2, after an odd number of reflections.