I believe it is 16 gauge, and ridiculously expensive to boot. Check out
this site (acessories4less.com) for higher gauge, cheaper flat cable. They don't appear to have the stuff I bought from them, but the new stuff is 15 or 13 gauge. Their customer service is first rate.
Edit: I can't tell if those wires are white or not! That could pose a problem... BTW, stay away from the self adhesive stuff; they sent me some of that by mistake and it was total crap. On the other hand, their new self adhesive wire doesn't look quite as bad, but the foam tape sold separately removes from the wall without taking the paint with it.
