watchOS 4.2 (build 15S5085b) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-10-30T22:07:18Z. The update package is 191.27 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: bd184a633fc73a315b3ab1eb83f6a808ceb5333a.zip.