The SI4421-A1-FT is a TxRx Only device manufactured by Silicon Labs. It comes in a 16-TSSOP (0.173", 4.40mm Width) package and has an operating temperature range of -40°C to 85°C. The device operates at frequencies of 315MHz, 434MHz, 868MHz, and 915MHz. The power output is 7dbm and the sensitivity is -110dBm. The device has a data rate of 256kbps and uses FSK modulation. It has a current transmitting range of 15mA to 24mA and a current receiving range of 11mA to 13mA. The device is ideal for use in General ISM applications and has SPI serial interfaces.