watchOS 4.2 (build 15S5102b) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm), released on 2017-11-17T18:18:07Z. The update package is 1.53 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f7743a9f4074b7dd924eea55fe4e036ae164b07c.zip.