As a brand who sells both T100 and T25 GTLS illuminated watches, we often get asked what the difference is.

Radiation content is measured in millicuries (mCi), therefore, all watches with a T25 mark contain no more than 25mCi of radiation content and similarly, watches with a T100 mark, contain no more than 100mCi.


All current Nite watches are fitted with GTLS tubes manufactured by the Swiss company mb-microtec. mb-microtec are widely regarded as the best manufacturers of GTLS tubes in the world and offer an extensive range of colour and size options. The size and colour of GTLS will ultimately determine the final mCi rating of each model.

Whilst there are differences between the amount of mCi in the T25 and T100 models, the idea of “which is better” is simply a choice of preference and taste.


It would be of interest to us to gauge from our customers, your preference, and whether this is determined by the situations you are in, activities you use the watch for, or simply down to personal taste?

Some prefer the T25 GTLS illumination due to its more understated look and design, whilst others are believers that if you are to purchase a tritium watch, then you will want as much illumination as possible, and opt for the T100 models.


Our new ICON series features both T25 and T100 models within it, on this page is a comparison of the T25 and T100 versions of the ICON-209S.