Fossil Watch Sport Smartwatch Black Silicone FTW4019. Fit for every style, this ultra lightweight 43mm Sport smartwatch features a black silicone strap, lets you track your heart rate, track your workout, even swimming, customise your dial and more. Smartwatches powered with Wear OS by Google are compatible with iPhone and Android phones. Wear OS by Google and other related marks are trademarks of Google LLC. Touchscreen smartwatches powered with Wear OS by Google require a phone running Android OS 4.4 or iOS 9.3 . Supported features may vary between platforms.