Max, I have such an Ideale with the same inscription on the alloy rails, but with the 9 and 0 where yours has "T" and "B". I'd guessing that all the alloy rails had that inscription. So you are obviously after the meaning of the "T" and "B". Since whomever decided on the letters speaks French, my guess at "Team bicycle" is just for fun. (I can't ride mine, having broken the allow seat clamp, so if your TB turns out not to be a collectors item, I'd love to know). Who knows why, but these are the most comfortable saddles I've ridden. I think the spring loaded tension adjustment, while it speaks now and then, may have something to do with it. I replaced it with a Brooks, which looks very similar, but isn't nearly as comfortable.