What is this mounting plate called? (Pic included)

https://youtu.be/oywJ6oz0z48?si=Kt86L9RiWajzM32-

The mount has captured nuts, that your accessories screw into.

 

Anything can be made to work, but we probably need more details. Can you post a picture of your phone mount?

 

Thanks for your response. The first picture is of my phone mount that I'm trying to install. It takes M5-80 screws. The second picture is of the spot on my DMM mount I'm trying to get it installed in (far left already has a hole with threads so I'll try to get it in there).

 

Easy! Buy a #10-32 screw, drill out the mount hole as needed, screw it down into that threaded hole...

 

Get a ball mount to fit the threads for the DMM hole, then get a short socket arm from RAM Mounts like this (https://www.amazon.com/Mount-Composite-Double-Socket-1-Inch/dp/B005KWPJ04), but sized for whatever diameter ball you mount to the DMM. Then get a double ball adapter similar to this (

$8 iHYTOON Double Ball Adapter Ball Mount 25.4mm(1") Compatible with RAM Dual Ball Socket Arms GPS Brackets(R11*1)

https://www.amazon.com/Double-Adapter-Compatible-Brackets-R11/dp/B0B1M713GW) with one ball sized to fit the ram mount socket and the other sized to fit the ball mount on the back of your phone mount. That will give you a lot more flexibility to adjust the height and the angle of the phone.

I have a phone mount and a rear view camera screen (on my bed rack to use as a rear view camera while driving) that I mounted this way. Mine are attached to a Tackform mount strip but the concept is the same.

 

Unfortunately a 10-32 screw is too small for my phone mount.

 

Should be able to fix that with an appropriate washer... or buy Ram ball adapters as suggested above.