Grothe test MISTRAL300

I needed a bell that:
1) has enough autonomy so that we do not have to change the batteries every 6 months
2) sounds loud enough to be heard in a large house
3) can be activated at a distance of 20 m through a cinder block wall
I did not step back to point 1) but likely to be held: there 2 AAA batteries (LR03) in the button box (instead of a button cell as seen in most products low-end), 4 LR14 batteries (C) in the case of the carillon, and the doc says they take 5 years.
Point 2) is acquired this product: a control sets the level. At bottom, it sounds strong. There is a choice of several melodies.
Point 3) too. I made the following test: chimes in a wooden garden shed (not an obstacle to the waves), doorbell at 50/60 meters, with cinderblock home in between. Reliable running. However the 250 meters stipulated in the doc seems very optimistic.
In the distance test, I used to listen back a DECT phone connected in intercom. When the handset was all against the chime, the scope was significantly reduced: very likely that blurs the DECT phone reception chime, although the frequencies are very different. So avoid the proximity of the carillon and a DECT phone, allow at least 1 meter.
My purchase follows that of a 30 chimes Extel I returned to casto (too low noise levels, a real Camelott). The employee assured me that all wireless doorbells were the same! Congratulations level of expertise or honesty because with Grothe there is evidence that not.
I therefore recommend this product, the only downside is the lack of rubber seal that would improve the sealing of the button box.