ArmourLite Watch Company is an American company based in Miami, Florida, that designs and manufactures the toughest and brightest Swiss tritium illuminated watches under the brands ArmourLite and Isobrite.

Swiss tritium illumination involves extremely tiny glass tubes that are filled with tritium gas, an isotope of hydrogen. The insides of the glass tubes are first coated with phosphorescent paint. The tubes are then filled with the tritium gas and laser sealed. The electrons of the tritium gas inside each glass tube continuously react with the phosphorescent paint resulting in a radio luminescent light source. The electrical reaction of this chemical process makes the phosphorescent paint glow constantly for several decades. No external power source or charging-by-light is necessary to maintain the glow. The glow is completely self-powered.

The T25 and T100 designations refer to the combined amount of tritium gas that is hermetically sealed in the glass tubes in a watch. T25 watches have up to 25 mCi (millicuries) of tritium gas in the watch whereas T100 means there is up to 100 mCi of tritium gas in the watch. T25 is found in the majority of tritium-illuminated watches. Since the Isobrite T100 watches hold more tritium gas than the aforementioned T25 watches do, the higher volume of gas results in more electrical energy being created. More electrical energy results in much brighter visible illumination. The best way to experience the difference in brightness is to actually compare a T25 watch versus a T100 watch in the dark.

T100 represents the latest technology in tritium watches and makes seeing the time in the dark much easier on the eyes. When transitioning from a bright environment to a dark environment, it takes the eyes time to adjust. With the increased visible brightness of T100, the transition is much easier on the eyes. Plus, as a person ages and the eyes don’t see as well, having T100 means the time can still be easily read in the dark.