: If you buy a unit with SOS/Satellite messaging (like inReach), you will need a monthly data plan.
: Basic navigation, small screens, no sensors like altimeters. buy handheld gps
: A "3-axis" compass shows your heading even while you are standing still. : If you buy a unit with SOS/Satellite
: Look for "TopoActive" or "Topo 100k" maps for topographical details. buy handheld gps