Hi, new member here. I independently wrote my own SX-PR manual before one was available, and Sonosax decided it was good enough to adopt. Thus, its existence on their site.
The published dimensions for the SX-PR4 are 236x180x44.5mm and 1.85kg with batteries of some sort. My example is more like 238x179x44.
It's possible to change the size in the field, but one needs the new size support rods that go through all module's corners and hold everything together, as well as having the multipin bus connectors between the new modules.
Other than that, I have no connection with Sonosax.
-Gary