Whoa, I surely didn't expect such an enthusiastic response to a grainy picture from my basement ;-).
The pouch itself comes without a bracket, I guess to keep it universal to all (XLab) single bottle mounts. I am using the XLab Delta 300. This thing is E-X-P-E-N-S-I-V-E ($100/£70). It comes with a Gorilla XT cage that is pretty much useless with the Aero Pouch. Maybe you can get one from XLab directly without the cage, I dunno. I am now using a cheap Planet-X Carbon Cage.
The fit is tight, I had to take off the transition hook and have about 2mm clearance to the little plastic clip under the saddle (see picture). The Delta 300 has 3 different holes to give more clearance if required, although putting the bottle further back might compromise aerodynamics. Alternatively you could take off the clip from the saddle and would have sufficient clearance either way. For me though everything fits perfectly with the Delta 300 fitted in the first hole. No rattling or other annoyances.