Quote Originally Posted by Santosan View Post
Assuming you are refering to a Garmin device, you can use the internal memory to copy two maps, one named gmapprom & the other gmapsupp. You can use your SD to copy two more files one named gmapsupp & the other gmapsup2 not gmapsupp2 Garmin won't recognize it.........
@vasile72
Santosan's post you quoted was made almost 2 years ago, and was not applicable for your Nuvi 255W at the time which then would support only one map named gmapsupp.img in the Garmin folder of the sd.

Quote Originally Posted by vasile72 View Post
On my Nuvi 255W the second map on SD card worked only with the name gmapsup1, not gmapsup2, so anyone interested could try this name also.
Thanks however for the tip on naming the map gmapsup with just one p at the end, because all other variants failed.
A recent fw upgade to your 255W has enabled a second map for sd, which must be named only gmapsup1.img as you have found.