The TXL2 transmitter and RXL2 receiver modules are described as half duplex multi-channel OEM radio modems in a SIL footprint. Operating in the European, license-free 433-MHz ISM frequency band, they provide a choice of five user-programmable channels, The modules can form transparent one-way radio data links supporting data rates of 9,600 bps over a line-of-sight range of 500m typical. Each can be assigned one of eight unique addresses, so that a multiple radio link network can be established, provided no two modules are attempting to transmit simultaneously on the same channel. The transmitter has an output power of 10 dBm (10 mW), while the receiver has a sensitivity of -107 dBm. The modules require a 5V power supply, drawing 28 mA for transmitting and 22 mA for receiving. Additionally, they have an operating temperature range of -20°C to +70°C. Radiometrix Ltd., Middlesex, England. +44 (0) 20 8909 9595.