Cellular keeps you connected with just your watch; Cellular and a barometric altimeter track how far and high you go. New dual-core processor for faster app performance; Ultimate sports watch and intelligent activity tracker. Swimproof so you're always ready for the pool or ocean; Aluminum or stainless steel case; watchOS 4 is even more intuitive and intelligent. Check apple.com/watch/cellular for participating wireless carriers and eligibility. Apple Watch Series 3 Cellular) requires an iPhone 6 or later with iOS 11 or later. Apple Watch and iPhone service provider must be the same. Not available with all service providers. Roaming is not available outside your provider network.coverage area.