Didn’t see this earlier! The screws are M3 which are standard with the Tray. Unfortunately, we could not align the screw holes to the dimensions of the Blue Robotics Tray as the transceiver and other modules take up a good amount of space and must be positioned in a very specific location. We will be looking into other ways of mounting though 
We also made changes so that we are using smaller power connectors.
Here is a link to it for anyone interested!