It might look the same as its predecessor, but the Apple Watch Series 9 has undergone serious change on the inside. It's powered by the new S9 chip, with a Neural Engine that enables several new features. Chief among those is a new double-tap gesture that has the wearer tap their thumb and index finger together to control the interface, and the ability to process Siri commands on-device. Its display is twice as bright in sunlight and more subtle in low-light situations, and its second-generation ultra-wideband chip enables precision finding for the iPhone. Notably, the Series 9 is Apple's first-ever carbon-neutral product, and the company is matching the expected energy use of each watch with an investment in renewable energy sources. The Series 9 is available in five aluminum and three stainless steel case options and is joined in the lineup by the Apple Watch Ultra 2, sporting the same S9 chip and the brightest display Apple has ever made.