Abstrakt Instruments VS-1 Assembly Manual page 19

Part 3: Attach DAC Board
(3) M3 x 6mm Phillips Narrow Pan Head Black Oxide Screw (pink) (Bag 1)
STEP 17: INSTALL PCB STACK TO FRONT PANEL
https://youtu.be/H4GvMA76W70
Part 1: Place 3 or 4 of the M9 fender washers on the encoder bushing to shim the panel to the correct distance from the encoder.
The exact number of washers will depend on how the encoder was installed. Usually 3 or 4 washers is what is needed.
(4) M9 Fender Washer (Bag 2)
Part 2: Mount the PCB stack into front panel
(21) M7 x 0.75 Panel Nut (green) (Bag 18)
(21) M7 x 0.75 Fender Washer (optional) (Bag 18)
Place the panel over the PCB stack. Make sure you have used the correct number of fender washers over the encoder to make
sure the front panel is the correct distance from the panelboard. Next, secure the panel with the panel nuts. You may want to install
only a few of the panel nuts at this time until the testing is complete. We don't use the fender washers for our retail VS-1's, but they
may give additional protection against scratching the front panel finish and screen-printing.