The new low cost M3 Adapters Pro are on the way here. It have less compatibility with GBA software, but offer great support for DS.
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The M3 Lite is the answer of M3 team to the Nintendo DS Lite. It is a full blown M3 adapter that will perfectly fit into your Nintendo DS Lite GBA cartrige slot without sticking out, and with all the functions of the M3 Adapter. It is using Micro SD card and comes with 3 cases (Black, White and Ice Blue) for perfect integration in the design of your Nintendo DS Lite.