This knob is used on the airbus TCAS panel

The other knob for the TCAS panel is also uploaded on my profile

You will find recess holes, these are a guide to where the grub screws need to be, you will need to drill these out further. I have also not placed a centre hole on the bottom of the knob, due to some people needing D shaped holes and others circle.

There is one grub screws at the back of the knob