watchOS 4.1 (build 15R5835d) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-10-09T17:05:02Z. The update package is 551.88 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: 9437e84d90c54332532c05767e7ad78b52aac3cb.zip.