Hobbypower 3DR Radio Wireless Telemetry Kit 915Mhz Module for APM2.6 APM2.7 Pixhawk PX4 The 3DR Radio telemetry system is designed as an open source Xbee replacement radio set, offering a lower price, longer range and superior performance to Xbee radios. It?s availabl in 433Mhz; and in the following configurations: serial board (for the air) and USB (for the ground). The radio is a 2-way half-duplex wireless communication system with a standard TTL UART interface, based on HopeRF's HM-TRP data link modules, and custom firmware that improves upon the modules' original features and performance. The SiK firmware includes a bootloader that permits radio firmware upgrades over the serial interface, and radio firmware with configurable parameters. Firmware upgrades and configuration are fully supported in the APM Mission Planner. Configuration is also possible through AT commands. Please note that it is up to you to make sure you are allowed to use these radio modules in your country. These devices can be used as short range licence expemp devices the UK under ESTI EN300 220, please refer to Ofcom IR2030 document, page 17. You will need to configure the device to comply with your countries regulations Free USB cable, use it to connect Android phone and tablet.