The Spot personal tracker is the worlds first satellite GPS messenger providing location based communications to family friends or professional services.
This is a great product to use in the field, practically worldwide. Spot can be setup (optional) to track your position over 24 hour period at a time, thus even if you lose satelite communications at the point of SOS, people can view your travels and determine an emergency from that information. This is something that cannot be done with an Emergency Beacon. Please note that this product is not legally a replacement for an EPIRB or PLB in a marine environment and requires a subscription.