Question about iROX Ebr707c

Hello
Here is a quote from the operating instructions:

Placement of a radio sensor
Place the receiving unit and the external transmitting units within
the possible range of the units, i.e. within a radius of max.
75 metres. Note that the actual range of the transmitters depends on
the materials used in the building and the position of the external
position of the external transmitting unit and the receiving station and may be
external influences (various radio transmitters and other sources of interference) may greatly
distance is greatly reduced compared to the optimum possible distance.
distance. If there is no reception, we recommend finding other positions for both the transmitter and the receiver.
for both the transmitter and the receiver. Sometimes it is enough to
just a few centimetres! Although the external transmitter units
weatherproof, you should not place them where they will be exposed to direct sunlight, rain or snow.
exposed to direct sunlight, rain or snow.

Greetings, neptun88