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GBA Transmitter
Nintendo is currently working on a device “related” to a pager that will be able to be used on the GBA. NinGC has reported that it is more akin to PDAs in the way that it uses thew same technology. There is a transmitter with the device that may be used for wireless GBA games. Heres some concept art:
Media was hotlinked from source (ningc.com) and missing
Source: http://www.ningc.com