"The Apple Watch Series 3 features a faster processor, the dual-core S3, Bluetooth 4.2 (compared to 4.0 on older models), a built-in altimeter for measuring flights of stairs climbed, increased RAM size, and is available in a variant with LTE cellular connectivity. Siri is able to speak on Apple Watch Series 3 due to the increased processing speed of the Watch.Series 3 features LTE cellular connectivity for the first time in an Apple Watch, enabling users to make phone calls, iMessage and stream Apple Music and Podcasts directly on the watch, independent of an iPhone. The LTE model comes with an eSIM and shares the same mobile number as the user's iPhone."
"Operating System: watchOS 4.0, upgradable to 8.1
Processor: Apple S3
Memory: 16GB 768MB RAM
Battery: Li-Ion 341 mAh (1.34 Wh), non-removable
Display Size: 1.65 inches
Display Resolution: 390 x 312 pixels
Connectivity: Wi-Fi 802.11 b/g/n, Bluetooth, GPS, NFC
Dimmensions: 42.5 x 36.4 x 11.4 mm (1.67 x 1.43 x 0.45 in)
Weight: 52.8 g (1.87 oz)"