watchOS 4.1 (build 15R5843a) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-10-16T17:05:55Z. The update package is 240.64 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: d8103558af577ecb525796b309627a846ea14ca7.zip.