.img files are intended for direct placement into the /Garmin folder on a GPS device's micro SD card.
“I found that North America and Europe probably take about 4-5 hours to download over wifi. It's significantly faster to download the maps onto the watch using Garmin Express on a PC.” Reddit · 4 years ago TOPO1a.7z
: Once extracted, you will typically find a .gmap folder or a .img file. : These files are popular alternatives to official
: These files are popular alternatives to official Garmin TopoActive maps because they are often free and can offer more specific local details or different contour intervals for hikers and cyclists. User Perspectives TOPO1a.7z
: Use a tool like 7-Zip or The Unarchiver to decompress the .7z file.
.gmap folders are generally for installation on a computer to be managed via Garmin MapManager.