You bought yours in France, so it is possible you bought one of the last few older models. They have ordered new ones with insulated cores too but I'm not sure they're there yet and I'm not sure if they've send their old units back to Dave or that they still sell the last few they have left. I can tell you which one you have if you post a photo of the top side though (with the top of the heater core visible), but so can Underdog-Dave or the guys who sold it to you. I don't know about that cloth though. All I can think of is that it is the insulating ceramic cloth, which would mean you have a newer UD. Again, ask Dave if you want a definitive answer. I think there has been enough talk about the red silicon paste in this thread, read back a little for all the details please. It's located outside of the air-path anyway, but if that isn't good enough you can always order a custom 'vegan' UD without it.