watchOS 4.1 (build 15R5843a) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-10-16T17:05:57Z. The update package is 138.05 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: 0244dd6fb2a9f43d086949b135b8a220d557d1cb.zip.