Well; it seems that from what I can make out it tries to make a large cab very stiff in order to drive the cabinet resonances out of the audible band. Am I correct? I remmember that Welbourne used to use them with those round horns and some people like the alignment for particular drivers. Thanks for the reply. I was wondering how big they have to get with an Altec 416 driver. And what exactly makes them desireable.