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
RP-SMA connector
Transparent serial link
MAVLink protocol framing
Frequency Hopping Spread Spectrum (FHSS) Configurable duty cycle
Configurable through Mission Planner & APM Planner