Apple unveiled the Apple Watch Series 3 on Tuesday.

It's the latest Apple Watch, and its big new feature is that it adds cellular connectivity, which allows users to send messages and receive phone calls even when an iPhone isn't nearby. The number is the same number that you use on an iPhone, Apple said. You can also stream music.

It looks similar to earlier Apple Watch models but has a red dot on the Digital Crown, which lets folks know it's the newer model.

Apple said Bluetooth and Wi-Fi are 50 percent more efficient to help save on battery life, and there's a new barometric sensor for better detecting flights of stairs. Apple used the display of the Apple Watch to serve as an antenna. The watch also features GPS and is swim proof. Apple promises up to 18 hours of battery life.

The device will launch in new finishes, including a new gray ceramic option, along with new bands from Nike and Apple.

During the announcement, Apple CEO Tim Cook said that the Apple Watch is now the number one watch in the world, ahead of even the most popular traditional brands. Cook also said customer satisfaction is at 97 percent.

The new Apple Watches will launch with watchOS 4, the latest software, which includes new health tracking functions, Siri recommendations, new watch faces and more.

Apple said the Apple Watch is the most-used heart-tracker in the world and it will now notify users when it detects an elevated heart rate when a user isn't active. It will, also listen to heart rhythm and will detect atrial fibrillation and alert a user if the heart rate starts to move into irregular rhythms. Data from the Apple Watch can be sent to a new Apple Watch Study that's begin run in tandem with Stanford Medicine, as first reported by CNBC, which will launch later this year.

Two versions of Series 3 will launch including one without cellular at $329 and a Series 3 with cellular at $399. The Apple Watch Series 1 will decrease in price to $249.

Orders begin Sept. 15 with availability on Sept. 22.