Smoke detectors for little money that also work

This smoke detector I bought because it in rent now duty is to have that in Baden-Württemberg. According to my information in all living rooms and bedrooms, as well as escape routes so hallways.

These smoke detectors are easy to mount using the supplied dowels and screws and the supplied 9V is serving now, just six months.

Whether the smoke alarm is working and triggers I have already tried with a Smoker. And there was enough in the vicinity to get away with it and the part went.