If you're referring to the eWin 2-in-1, it doesn't use its own microSD card at all. The eWin 2-in-1 is a slot 2 GBA expansion cart that is used in conjunction with a slot 1 flash cart such as the DSTT. You store the GBA games on the slot 1 flash cart's microSD card. Most slot 1 flash carts (including the DSTT) support microSDHC, which be more than 2GB.
Oh I know that, I own an edge card I know how they work, but I recently found a site that has the DSTT GBA EWIN gba cart and it states that using 2 gig SDHC with it from your slot 1 cards, the gba cart may not work properly with it, which is why I was asking someone if they have one of these and use more than 2 gig micro card with it. here read this....
7. Please note 4GB microSDHC card might not work properly with DSTT GBA & Explorer expansion card. Use 2GB normal microSD card instead. Or use EDGE
This is why I was asking about it before I bought it cause I have 4 and 8 gig cards.