Nuvi Internal Memory

1) gmapprom.img - Preloaded Map
2) gmapprom1.img - Preloaded 2 Map (If there is)
3) gmapsupp.img - Secondary Map
4) gmapoem.img - OEM Supp map
5) gmapsup2.img - Secondary 2 Map
6) gmaptz.img - Time Zone Map
7) gmap3d.img - 3D Image Map (7x5 Series)
8) gmapbmap.img - garmin Base map

Storage Card :
1) gmapsupp.img - Secondary Map
2)gmap3d1.img - as second 3D Buildings Map (7x5 series )

in sd put it in a folder named Garmin ( just one map per sd is supported)