Why do the devices have a removable battery?

The batteries of the devices can be quickly exchanged for repair purposes or for seamless further work.

The battery is protected so that no sparks can occur even when changing batteries in the Ex zone, but the higher-level ATEX directive still applies, which states that batteries must not be changed in the Ex zone.
The removable battery is designed to facilitate maintenance (battery replacement, SIM or Micro-SD card exchange) and has been provided with 2 screws for safety reasons, so that it does not fall off accidentally in the event of a fall.