Built-in transmitter for control by up to 4 external buttons. The transmitter fits into a switch box behind an existing button/switch, and is therefore used to expand an existing switch range with radio functionality. Due to the ability to transmit at adjustable intervals, this device is ideally suited to reliably transmit long-lasting switching states (such as motion detectors, timers, thermostats, etc.). For this operating mode, a follow-up time corresponding to the transmission interval can be set on the respective radio receivers. 3 operating modes (button mode, interval transmission with 10s or 30s, only 3 transmission intervals). This variant is supplied with a battery (CR2032)., Compatible products: radio receiver FE3 series, radio dimmer FD3 series, repeater FV2 R., Dimensions: 43x43x33mm, 3V DC, 4 channels