Cockpit Vents

I am cutting metal for my panel and forgot to identify the area required for the cockpit vents. I am planning to use Stein's 1 1/4 vents here:

http://steinair.com/storedetail.cfm?productid=311

but do not know the maximun diameter. I know a 2 inch hose mounts on the rear, but the flange is larger. Anyone know the maximun diameter including the flange or have one they can measure or know where I can look it up???

Thanks - Greg

The flange sits on the outside, it doesn't go in the hole so you don't need to worry about that. Hole size is 2". Flange is another 1/8" or so.

Thanks, understand the hole needs to be 2 inch. Trying to figure out the diameter of the front of the flange to ensure I leave enough room for my switches and labeling. If it is an 1/8 or so, would that meant the distance across the front is 2.25 inches? Anyone have a measurement??

Thanks - Greg