"Mark-25" with complete field dieléctrico. The whole apparent field is covered with quartz that substitutes the conventional mirrors. The images of the horizon and the star combine in an alone field for a simpler and trustworthy vision, still in the worst conditions. A mineral special covering is selective for the different lengths of waves. The horizon appears in the region of a color and the stars and the Sun in other one. Framework in plastic reinforced for major safety in the observations.A system LED of great performance, it illuminates permanently the graduated sector and the drum with tenuous light. The LED will work during the whole life of the sextant, so with the batteries that it takes, it lasts 10 times more than with conventional bulbs. With switch protected with a cap of vinyl.