Comparison Xiaomi Aqara Hub M2 vs Xiaomi Smart Home Hub 2

The presence of its own siren in the standard configuration of the set.

The siren provides an audible and, in some models, a light alarm; sometimes this is enough to stop an encroachment on a protected object or to attract the attention of security / law enforcement officers. Such equipment can also be purchased separately (if there is a corresponding output, see "Control panel options"). However, in most cases it is more convenient to buy a system that was originally equipped with a siren: this will allow you not to worry about compatibility, and complete sirens usually give out more than a decent number of decibels (see "Siren volume").

The air temperature range in which the alarm components maintain normal operation.

This parameter is important first of all in cases where the alarm is planned to be used outdoors or in unheated rooms. Particular attention in such cases should be paid to whether the system can work at sub-zero temperatures. If we are talking about room temperatures (plus or minus), then you can’t really look at the claimed temperature range — almost any alarm is suitable for such conditions.