Luminous material in Sandoz?

Hi gang,

Does anyone know what sort of luminous material Sandoz uses in their watches, particularly in the Explorer?

I just received one of these beauties from Reto and I'm writing a review. I like to be reasonably thorough, and it occurred to me that I really have no idea what lights this thing up. I know it isn't a good performer; it doesn't seem to hold daylight for more than a small handful of seconds.

I'm thinking it may be a really poor luminous compound laced with tritium because it does seem to have a very faint persistent glow to it. Anyone know for certain?