From 4 detectors is already an unusual and makes false alarms for no apparent reason

I ordered the product on 12/07/2013 and today (24.08.2013) is already the first smoke detector dropped out, making false alarms at once, I was sitting in the room and was pretty scared! I then quickly grasped the ladder and removed the battery, so you finally have peace. Now 3 smoke detectors of this sort in operation in other rooms and my confidence in this smoke detector is really not large.

I would advise against this action after the purchase.

Addendum: There are since 2010 (!!!) a "recall" or a warning of this product:
[...]
In my case RAPEX 16/2010 with the model HS-103 as on the English side described under No. 34:
[...]

The Amazon is such a thing sold really bad. After all, it is about the safety and possibly human lives! This smoke alarm should be sold under "dummy with pseudo-function".