Apple Watch Series 12 and Ultra 4 Firmware Leaks Reveal Codenames, Touch ID References, and Multi-Day Battery

A wave of firmware leaks has given the clearest picture yet of what Apple is planning for its September 2026 watch lineup. Internal watchOS builds reference three new codenames — and at least one blockbuster feature.

The Codenames

• N237: Apple Watch Series 12, Wi-Fi variant
• N238: Apple Watch Series 12, cellular variant
• N240: Apple Watch Ultra 4

The presence of all three models in the same firmware snapshot confirms a coordinated refresh — Apple will announce both lines together, not stagger them.

Touch ID ("AppleMesa")

Developers have found references to "AppleMesa" — Apple{"'"}s internal codename for Touch ID — inside leaked watchOS firmware for 2026 models. While Touch ID on the Series 12 remains uncertain, the feature appears more plausible for the Ultra 4, which has more physical space for a sensor. If confirmed, it would be the first biometric unlock on an Apple Watch beyond wrist detection.

Other Rumored Features

• Multi-day battery: The Ultra 4 is linked to battery improvements that could stretch past two full days of normal use
• Blood pressure monitoring: Building on the FDA-reviewed sensors from Series 11, the new models may offer more detailed cardiovascular tracking
• MicroLED display option: At least one model may ship with Apple{"'"}s long-rumored microLED panel, offering better brightness and efficiency
• New chip: The Series 12 is expected to finally move off the S9 silicon that has been used for three consecutive generations

What This Means for Buyers

Apple typically sends media invites in the last week of August, with the keynote landing in the second week of September. If you{"'"}re considering an Apple Watch purchase today, the Series 11 at $299 on Amazon is a strong deal — but waiting 5-6 weeks could net you Touch ID, a new chip, and multi-day battery. The Ultra 3 at $640 is harder to recommend with the Ultra 4 this close. See our fall smartwatch comparison or browse all smartwatches.