PBM-04/U bi-stable relay is used to control lighting or any other device with the help of unipolar parallel connected switches. Another push of any switch causes actuation or disengagement of devices connected to output terminals (change in relay status). The device enables to use typical unipolar switches connected to IN inlet and switches with illumination connected to IN’ inlets (tripping only from L line for 230V voltage). Structure of the relay enables to record the current status in case of loss of supply voltage. Zero power consumption stands as an important feature of the device.