eldenh, I bet he's talking about Slime. Either that or something similar. If you don't know what he's(or me, for that fact) talking about, it's green and it comes in a bottel and you pour it in your tube. You have to take out your valve core first. It's supposed to protect against punctures, but I don't it'll work very good against pinch flats as they tend to look like someone took a knife and cut two slits in the tube, side by side. The stuff adds a little weight. The other thing he might be talking about(but I highly doubt it) is a bib mousse. That's actually a foam insert that you use instead of a tube. They're heavier than even a Slime filled tube, and from what I've heard, a royal PITA (pain-in-the-@$$) to put on/in. Not to mention a little expensive (about $170 ea.). If he's talking about something else entirely, have no idea what it is.