Somewear Global Hotspot

Somewear pairs with your smartphone and turns it into a satellite-connected device — you use your phone's interface rather than the device's own screen. The hardware is 47g, making it the lightest option here. Iridium network gives it the same global coverage as Garmin. The catch is dependency on your phone: if the phone battery dies, so does your messaging capability. Two-way messaging works, and the SOS function is full-featured. At $199 with plans from $25/month, it's priced between SPOT and Garmin.