The SE+ is the entry-level model, which will retail for $400/£400 when it becomes available later this quarter. It offers "pole to pole" GPS guidance, messaging and GEOS SOS alerts. Users can send text messages to any cellphone number, email address or other InReach device, regardless of current cell coverage. The Explorer+, which costs $450/£450, incorporates all of the SE+'s features as well as DeLorme topographic maps, built-in digital compass, barometric altimeter and an accelerometer. Each manages 100 hours of battery life in active tracking mode and up to 30 days in standby/power saver.

You will, however, need a subscription to the Iridium satellite network to get these features to work. Annual or monthly subscription plans are available; annual rates run from $12/£13 to $80/£85 per month (plus an activation fee); monthly plans will set you back $15/£17 to $100/£105 per month.

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