Offer this page it says "silent button" but it is false because in the instructions it says "only Toba model" and here is the Baikal model. It is also indicated autonomy 5 years for the battery, however it is a simple alkaline battery that is delivered and whose template is not in the technical data for a battery life of 5 years of the unit. Apart from that the workmanship is good. To 30 m2.