Grab a Series 4 Apple Watch for 13 percent off—now $349. The Apple Watch changed my exercise habits, how I monitor my health, and decreased the amount of time I spend on my phone. This 40mm Space Gray, GPS-only model has louder speakers than previous models and a brighter face than the Series 3. The Series 4 comes with the built-in electrical heart sensor, fall detection, and lasts for up to 18 hours on a single charge. $349.