Main features:

Totally wireless communication

Could interconnect up to 20 units. When one unit sound, It will emit signal to others with the same coding and start it to alarm.

Two sets dip switches for coding the transmit and receive

Frequency to prevent interference with other RF base.

Low battery warning

DIY unit, easy installation

5 years warranty

Supplied with 4x AA batteries, wall plugs & screws

CE, R&TTE approval