I'd STRONGLY advise NOT getting that stem.
For starters, the two-bolt clamp is a pain in the arse.
The clamp rarely grips bars tight enough to be usefull.
After you've done it up and undone it any more than 6-7 times, the top half of the clamp cracks where they've counterbored too deep and nearly come out the other side, then it snaps off when you next try and do it up.
Finally, they look like shite
Real nice shape for these short Onza frames - had one on my Comp for a while - but other than the geometry, they majorly suck.
This is going off personal experience, and Josh had the EXACT same issues. Both died within a couple of months use.