Some pilots want a short lanyard to secure the Blueflyvario to a flight deck or harness. This is the recommended method for the v12 models.
Start by marking the location for a few holes at the end of the vario opposite the USB connector. When you drill through the case you need to avoid the screws and the pcb.
Next drill two holes the same diameter as your lanyard. I use some old paraglinding line.
Finish by adding your lanyard. Note that the line inside the case is in the gap at the end of the battery, between the two screws.