A:Answer On units with SD memory card slot, you can add memory for additional maps, voices and, in some cases, pictures & music.
On a PREVIOUS model, it kept giving me a message to use an SD memory card before I could update to a new map.
Be sure to note maximum SD card memory size!
The PREVIOUS model SD max was 4Gb, anything larger was just wasted space/$$.
The info the GPS saves on the card is proprietary so don't go thinking you can go and view the data on a PC/Etc. Does not work that way. Hope this helps you!