Polar's latest multisport watch promises a battery life that could sate the most dedicated of fitness enthusiasts. The company claims Grit X can run for up to 40 hours on a single charge, and that's with all of its features activated. With power save options, the Grit X offers up to 100 hours of juice before you'll need to recharge it.
You might not want to use all of the features at once in any case, but even so, Grit X includes a wide array of tools. Along with the GPS tracker, compass, altimeter and wrist-based heart rate monitor, there's a Hill Splitter feature, which tracks your uphill and downhill segments with detailed stats.