Originally Posted by AlbertaCowboy
(From the website): Earl comes preloaded with 100k resolution topo base maps covering the United States, Canada and Mexico. Upgrade Earl to 24k resolution topo maps on microSD for an additional $50.
I upgraded to the 24K when I ordered mine way back. I believe I recall that the upgraded maps come on a preloaded SD card, while the 100K are loaded onto EARL's memory.