Like the Game Boy Advance Game Link Cable, this device allows for multiplayer gaming with the Game Boy Advance, and attaches via the External Extension Connector. The range of this adapter is short compared to the built-in wireless function of the Nintendo DS; Nintendo recommends players stay within 10 ft. (about 3m) of each other for best results. Note that due to the Game Boy Micro's different style link cable port, the Game Boy Advance Wireless Adapter will not attach to it. However, a Game Boy Micro Wireless Adapter is available for the Micro which is compatible for linking with the Game Boy Advance Wireless Adapter. Neither wireless adapter can connect with the Nintendo DS since the DS does not support multiplayer mode in Game Boy Advance games.
Source: Wikipedia, "Game Boy Advance Wireless Adapter", available under the CC-BY-SA License.