I have an RSeat P1 and while the tubular construction is rock solid, it does make mounting add-ons more difficult than a profile rig.  So, like anyone would,  i bolted a slab of oak to it. The oak shelf lets me use a trackpad, streamdeck, and now the PXN-CB1 button box with this cool mounting bracket you're looking at. 

So, If you hacked your rig by fitting a shelf, this bracket/button box combo could be for you.