Qiyun 1Pc TTL 3DRobotics 3DR Radio Telemetry Kit 433Mhz APM APM2 APM2.5

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 available 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 boot loader 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.