This is the GPS watch that grows with you. Start out with the basic Fenix watch that already packs advanced features like an altimeter, barometer, and compass to keep you on track and keep track of your stats on the mountain. Garmin's famous GPS capabilities are also built into the Fenix and work with the compass, watch, and altimeter to automatically calibrate the sensors as you go for the most accurate readings possible. The advanced display combined with the built-in GPS keeps track of where you're going and where you've been. When it's time to head back, just switch the Fenix to trackback mode and follow the line on your watch back to the trailhead. When you’re ready to expand your athletic portfolio, the Fenix's wireless capabilities work with optional attachments like a heart rate monitor to help you train for competition and even a wireless speed and cadence sensor for cycling and mountain biking.