These are essentially the same hardware as the older Series 2.5, but have updated firmware. They will work with Series 2.5 modules if you update the firmware through X-CTU.
Not sure which XBee module or accessory is right for you? Check out our XBee Buying Guide!
Note: If you are looking for a simple point-to-point configuration, you might want to try the Series 1 instead. The Series 2 requires considerable setup and configuration. We highly recommend Building Wireless Sensor Networks as a guide for setting up mesh networks.
Note: Series 1 and Series 2 XBee modules have the same pin-out. However, Series 1 modules cannot communicate with Series 2 modules.
Note: If you are using these outside of the United States, please check with your local laws regarding radio communication.