I used it to mount the switch under my desk. Holes are for 3mm screws.

The switch is held in place by the snaps in the corners. Be a little careful about inserting the device into a mounted frame (tip: push it leveled rather than at an angle). Depending in the fillament and print quality, the snaps are somewhat brittle. Once inserted, there is no more stress on them so it's just the insertion and removal of the device is when they are stressed the most.