The Apple Watch Series 1 and Apple Watch Series 2 are the second-generation models of the Apple Watch and was released on September 16, 2016.[2][3] They use the Apple S1P and Apple S2 SIPs (System in Package), respectively,[4] and the Series 2 has a built-in GPS and twice the display brightness of the previous generation for easier outdoor readability. The Apple Watch Series 1 and 2 requires at least an iPhone 5 with iOS 10 or later.[5]