Great for use with Arduinos or other microcontrollers Use a simple wire antenna or spot for uFL or SMA radio connector Easiest to work with of the four radio modules; well known and understood Uses the amateur or license-free ISM band (ITU 'Europe' license-free ISM or ITU 'American' amateur with limitations) All radios are sold individually and can only talk to radios of the same part number. E.g. RFM69 900 MHz can only talk to RFM69 900 MHz