Advantech HMI-640S - Manual (Page 19)

Chapter 1 General Information 9
1.7 Mounting
If you want to panel mount your HMI-640S, use the four brackets that
are included within your package. First, fit the HMI-640S body onto
the cutout panel and hold it temporarily in place with your hands.
Then, insert each bracket into the four keyholes on both sides of the
HMI-640S rear case, and use appropriate screws to fix the HMI-640S
body on the cutout panel.