what size of a Micro SD Card
what is the smallest Micro SD in a GPS
You would want to use a 4 to 8 Gig SD card for this. The map updates will eventually use up the space on the unit and you will need one to continue getting map updates. There is no smallest, it is just a matter of what you need for the future updates. Also if you want to store other things on the GPS you need to take that into account too.