Apple (AAPL) announced updates to its entire Apple Watch lineup during its annual iPhone event at its Cupertino, Calif., headquarters on Monday. The changes include a new Apple Watch Series 10 and updates to its Apple Watch Ultra 2.

The Apple Watch Series 10, which starts at $399, gets the biggest changes of the lot, with Apple increasing the display size of the 41-millimeter model to 42 mm and the previous 45-mm edition to 46 mm. The watches also sport slimmer casings than their predecessors.

The displays offer up to 30% more screen area than the Apple Watch Series 6, giving users space to view more text and making it easier to type messages, enter passcodes, and check emails.

The Apple Watch also gets rounded corners, giving it a more streamlined look, and Apple's first-ever wide-angle OLED display that's designed to look 40% brighter when viewed at an angle. It also updates every second rather than once a minute.

Despite its larger, brighter displays, Apple says the Apple Watch is its thinnest smartwatch yet. What's more, it features a new speaker that you can finally use to play audio.

On the battery front, Apple says the Apple Watch can charge to 80% in just 30 minutes. So, if you use the watch to track your sleep, you can drop it onto its charger and top it off before heading out the door for the day.

Inside, the Apple Watch is powered by Apple's new S10 chip, which enables things like on-board Siri, Crash Detection, and Double Tap. Apple says the Series 10 also uses new neural networks for improved phone calls.

Health tracking features are a major selling point for the Apple Watch, and Apple is expanding on that with a new sleep apnea detection function that will alert users if it determines they are exhibiting signs of a sleep disorder and tell them they should visit a doctor. I've got sleep apnea and use a CPAP machine every night, so I'll be able to tell how well the watch is able to pick up the condition.

The detection algorithm uses machine learning and clinic-grade sleep apnea tests. Apple says it expects clearance from the FDA soon, and it will be available in more than 150 regions. The feature is also coming to the Apple Watch Series 9 and Apple Watch Ultra 2.

On fitness tracking, Apple says the Series 10 gets a new depth detection function for diving and snorkeling. The company is also introducing tides information as part of watchOS 11 to provide users with information before they hit the beach. There's also improved tracking for paddling on the water.

The $799 Apple Watch Ultra 2 doesn't get much in terms of physical updates, though Apple is adding a new satin black finish. The company is positioning the Ultra 2 as the ultimate sports watch in Apple's portfolio, with Apple saying it's great for running, biking, swimming, golfing, and skiing.

Since its debut 10 years ago, the Apple Watch line has become one of Apple's most popular iPhone accessories and one of the bestselling smartwatches in the world. Apple doesn't provide overall Apple Watch revenue and instead counts it as part of its Wearables, Home, and Accessories business.

In its most recent quarter, the segment brought in $8 billion, down from $8.2 billion in the same quarter last year. Across all of 2023, Apple's Wearables business accounted for $39.8 billion of the company's $383 billion in sales. That was more than its Mac and iPad segments but well below its iPhone business, which brought in $200 billion for the year.

Email Daniel Howley at dhowley@yahoofinance.com. Follow him on Twitter at @DanielHowley.

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