I figure since I have owned several Aperture panels over the years, and since Stillpoints does an absolutely horrible job of providing any photos or details, that I would show you the differences...
Up to you Myles... the border I referred to thinking was foam is actually hard... so probably wood. Its the same 2" in from the outside edge of the panel on the old and new. Therefore... it traps from the same area
I hope some one finds the photos helpful in their search for knowledge. I have owned as many as 12 aperture panels at once and can say that they certainly do work. Can I hear any difference between the mk1 and 2... absolutely not. I do appreciate the marginally better quality and flush design though. And I do mean marginal.
Okay, guys, some basic math to provide some accuracy with respect to comments above:
Area = length x width
Volume = length x width x depth
As this is an acoustical panel that absorbs acoustical energy at different frequencies (wavelegths), my guess is that it is the volume of the panel that is one of the key metrics.