Face markings

[johane]

Hi
The marking on the very bottom of the face is something that has made me somewhat confused, if you can help me to clear this up it would be appriciated.

If you buy a Rolex today it says SWISS MADE and on older models it says SWISS -T<25. As I understand it, it has to do with the material used to make the hands and hour markings glow in the dark, now they use Luminova but before they used some other material (Tritium?)

When was the changeover year? I have a T-serial Explorer with the old marking but I saw a L-serial 16618 yesterday with SWISS MADE. Has the face of the 16618 been changed or did they change the system in different years for different models?

Thanks for your help