This is the new standard for the international 406 satellite frequency emergency Personal Locator Beacon (PLB) to trigger emergency rescue!
ACR Personal Locator Beacons are the ultimate solution for rapid rescue assistance in remote locations if you are facing life-threatening situations or hopelessly lost. Here's the straight scoop: Both of the TerraFix 406 PLB models are waterproof, float, and have more (40 hrs) battery life than the new ACR MicroFix 406 GPS PLB (31 hrs). The MicroFix is more compact and lighter by a couple ounces, but it does not float on its own. It can be activated with one button, whereas the TerraFix requires simultaneously pushing the two blue buttons. Unless you must have ultralite & ultracompact or only have one hand, save yourself $100 and get the ACR TerraFix 406 GPS I/O PLB, it is a sturdier unit.

By the way, the ACR AquaFix 406 GPS I/O EPIRB is the SAME exact unit in blue (like water). Either can be used on land or water. The really cool thing about this whole program is your ability to enter your trip profile, boat info, gear and group appearance, route plan, etc. in your personal PLB web page on the NOAA site! If you need rescue and trip the satellite, your PLB unit's unique electronic serial number and your GPS coordinates are transmitted immediately. Within 3 minutes, the nearest Rescue Command Center will know exactly what they are looking for, what you were supposed to be doing, and where you are within about 100 yards! (You had better really need them, 'cause they'll be coming fast!)