Overview    This Holybro SiK Telemetry Radio is a small, light and inexpensive open source radio platform that typically allows ranges of better than 300m “out of the box” (the range can be extended to several kilometres with the use of a patch antenna on the ground). This radio is plug-n-play all Pixhawk Standard and other Flight Controller, providing the easiest ways to setup a telemetry connection between your Autopilot and a ground  station. It uses open source firmware which has been specially designed to work well with MAVLink packets and to be integrated with the Mission Planner, Ardupilot, QGroundControl, PX4 Autopilot. The radios can be either 915Mhz or 433Mhz and you should purchase the model which is appropriate for your country/region.  Features       Open-source SIK firmware     Plug-n-play for Pixhawk Standard Flight Controllers     Easiest way to connect your Autopilot and Ground Station     Interchangeable air and ground radio     Micro-USB port (Type-C Adapter Cable Included)     6-position JST-GH connector          Specification       100 mW maximum output power (adjustable) -117 dBm receive sensitivity     RP-SMA connector     2-way full-duplex communication through adaptive TDM UART interface     Transparent serial link     MAVLink protocol framing     Frequency Hopping Spread Spectrum (FHSS) Configurable duty cycle     Error correction corrects up to 25% of bit errors Open-source SIK firmware     Configurable through Mission Planner & APM Planner     FT230X / FT231X is a USB to BASIC UART IC          Dimensions       28 x 53 x 10.7mm (without antenna)     SiK Telemetry Radio V3 -433MHz(1pc):20.7g  SiK Telemetry Radio V3 -915MHz(1pc):22.7g        Electrical Data       Supply voltage: 5V DC (from USB or JST-GH)      Transmit current: 100 mA at 20dBm     Receive current: 25 mA     Serial interface: 3.3 V UART       FCC IDENTIFIER: 2AP22-HT03-V3 Package Included   Radio modules with antennas *2 Micro-USB to USB-A cable *1 Micro-USB to Micro-USB OTG adapter cable *1 Micro USB to Type C Adapter JST-GH-6P to JST-GH-6P cable *1 (for Pixhawk Standard FC) JST-GH-6P to Molex DF13 6P (for Pix32, Pixhawk 2.4.6, etc.)