Apple Watch Ultra 4 launches with upgraded S11 chip and improved health sensors that measure heart rate every 5 seconds, enabling more frequent HRV tracking. Battery life exceeds 2 days in standard use (84 hours in power-saving mode), and new features include body readiness scoring (Readiness), improved step counting, and AI-powered audio intelligence for hearing assistance and conversation transcription. Starting price: 29,900 THB, though Thai market availability date is not yet confirmed.