When you need to use a SMT device on a breadboard, in your project, or while creating a prototype. When you don't have the time to lay out a board just to use a SMT device. Then you need to use one of these adapters - they are simple to use, come un-assembled or assembled and with machine pins or wire wrap pins. We carry matching stencils, for most of these converter boards, along with solder paste to give you a perfect solder connection.
In trying to use the XBee Explorer with the Ardupilot Mega (APM) 2.5, I found that the telemetry port on APM produced the 0-5V serial signal; but when connected to the Xbee Explorer, the APM could not sink enough current to vary the signal reaching the modem.