Conrad Electronic ASH888 Notice D'emploi page 29

When drilling or tightening screws, make sure not to damage
any power supply lines, gas or water pipes, as this might
involve life-threatening danger!
Now, the completely mounted outdoor sensor is inserted into the mounting
support as far as it will go in vertical direction.
If the outdoor sensor has to be removed (e.g. for battery replacement),
turn it to the left by 90° (as shown in the figure below) until there is an
audible click. Then pull it out of the mounting support in forward direction.
29