watchOS 4.1 (build 15R5835d) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2017-10-09T17:05:09Z. The update package is 565.36 MB. This is a delta (partial) update that requires 3.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 744b01c7e8a9144efeeb2955fa305a9276b00636.zip.