Oris mainly uses Super-LumiNova® and, for diver’s watches, Tritium SPO. Super-LumiNova® is a non-radioactive pigment that can shine for a long time. This phosphorescent pigment works like a light-battery. The material acquires its energy from daylight or other sources of light. In darkness, it can be luminous for several hours, depending on the quantity of the material. Tritium SPO is a self-luminous material, activated by the only slightly radioactive isotope tritium. The half-life of tritium luminous pigments is four to five years. The extremely light beta radiation is sufficient to illuminate the zinc sulphur crystals, but it is too weak to radiate through the case or crystal. According to ISO specification No. 3157-199l (E), tritium is not harmful to human beings or animals. Tritium’s main advantage is its long luminescence duration of eight to 10 hours, compared to the luminescence duration of Super-LumiNova® of four to six hours.