Apple is using a 128GB NAND flash die in Apple Watch Series 12 and Ultra 4 models, claims a Chinese hardware researcher, despite both devices officially offering only 64GB of storage. It's unclear why Apple would limit the accessible capacity, but it could conceivably be reserving some of it for intensive sensor data read/writes or as a durability buffer.

Apple Watch Series 12 and Ultra 4 add five-second heart-rate readings, more frequent HRV tracking, daytime vitals, and a Readiness score. Here’s what changes.