Apple Watch Series 12 and Ultra 4 review: More personal than ever

Apple Watch Series 12 and Ultra 4 get a new Health Sensing System with redesigned electrodes, photodiodes and green LEDs. Heart rate is measured every 5 seconds even during movement, with accuracy above rivals per a study of 1,000+ participants. Series 12 comes in aluminum, titanium and ceramic.

• Heart rate measured every 5 seconds instead of 5 minutes, including during movement
• Electrodes gained larger contact area, photodiodes arranged in a ring
• Series 12 comes in aluminum, titanium and ceramic (Night Blue, Pearl White)
• Aluminum version moved to Ceramic Shield 2 glass