Recessed tweeter mount uses standard 1-3/4" hole saw
DDC™ (Discreet Dual Clamp) Tweeter Mounting provides concentric clamping pressure around the perimeter of the mounting hole. This results in maximum ease of installation.
I tried the Tech Support, my luck with this on many other sites is pretty hit or miss at best. To my surprise, I received a response in less than two days and it obviously showed that someone with some intelligence and knowledge actually carefully read what I wrote and made a reply that made sense.