XBee Breakout Boards
XBee modules are easy to use, but they require a little love before they will fit into a typical Arduino project because their pin spacing is 2mm instead of Arduino-compatible 0.1". The solution is a small PCB called a breakout board, a way of creating a tiny circuit that can be plugged in to an Arduino.
The wimpiest of these is simply a PCB (printed circuit board) equipped with pins with the right spacing for breadboarding. However, more robust breakout boards, such as Adafruit’s (P/N 126, previously shown in Figure 4.2), have a voltage regulator and status LEDs to keep your radio from getting fried.