Topo1a.7z -

.img files are intended for direct placement into the /Garmin folder on a GPS device's micro SD card.

These tutorials provide step-by-step guidance on extracting map archives and installing them onto your GPS device: How to Import TOPO to a Garmin GPS YouTube · ExpertVillage Leaf Group TOPO1a.7z

According to community feedback on similar topographical downloads: TOPO1a.7z

.gmap folders are generally for installation on a computer to be managed via Garmin MapManager. TOPO1a.7z