From what I can gather, they're built up on the Maxxis High Roller carcass with On One's own tread pattern, but I stand to be corrected.
Decent review here, I'll probably end up buying a set of Smorgasboard AND Hans Dampf, lol - http://bikemagic.com/gear/on-one-smorgasbord-tyre-review.html
That is a decent review, and they are tempting me because I'm skint.. But I think I'd still prefer to get the HD's for now.
, little bit more than the Rockrider, but I like it a bit more. Compared all the components and they're all pretty much the same spec with just personal preference being the difference.

Can't decide whether to buy superstar/uberbike or formula pads :S