The main physical difference between the Up3 and the Up4 is that the Up4 is currently available in silver and black while the Up3 is ready to wear in multiple colors. The Up4 is made of TPU rubber and the rigid sensor hub that's encased in anodized aluminum. The Up4 is "one size fits most," measuring 8.6 x 0.5 x 0.4 inches, but you can adjust the placement of the hook to comfortably accommodate a larger wrist.
One you download the Up companion app for Android and iOS and connect the Up4 to your account, you can put the wristband on and go about your day. The Up4 tracks all of your activity, including steps, calories, and active time, and syncs the most current data to the app every time you open it.
Resting heart rate is taken right before you get out of bed in the morning, and it can be a good, glanceable indicator of your overall health. Those with resting heart rates lower than 60 bpm tend to be more active daily, resulting in a more efficient heart that doesn't need to work as hard as others to pump blood throughout the body.
The standout feature of the Up4 is American Express integration. The bottom part of the band has a barely noticeable NFC logo, which you hold up to any NFC reader to pay using your AmEx card. Place your wrist near a payment machine with this icon facing up to pay with your American Express card.First, you must connect your account through the Up app (which takes only a few minutes), but you can only choose one AmEx card and you can only go through the setup process once—so choose wisely.