"The Apple Watch Series 4 features larger displays with thinner bezels and rounded corners, a slightly rounder, thinner chassis with a redesigned ceramic back, a new S4 64-bit dual-core processor capable of up to double the S3's performance, upgraded 16 GB storage, new options for watch face customization, and a new electrical heart sensor which works by measuring the potential difference between the wrist and a finger from the opposing hand into the S4 Module over 30 seconds. The ECG system has received clearance from the United States Food and Drug Administration, a first ever for a consumer device, and is supported by the American Heart Association. This device can also detect falls and will automatically contact emergency services unless the user cancels the outgoing call. The microphone was moved to the opposite side between the side button and the digital crown to improve call quality. Other changes include the digital crown incorporating haptic feedback with the Apple Haptic Engine and includes the new Apple-designed W3 wireless chip."
"Operating System: watchOS 5.0, upgradable to 8.3
Processor: Apple S4
Memory: 16GB 1GB RAM
Battery: Li-Ion 225 mAh (0.86 Wh), non-removable
Display Size: 1.57 inches
Display Resolution: 394 x 324 pixels
Connectivity: Wi-Fi 802.11 b/g/n, dual-band, Bluetooth, GPS, NFC
Dimmensions: 40 x 34 x 10.7 mm (1.57 x 1.34 x 0.42 in)
Weight: 40 g (1.41 oz)"