watchOS 4.1 (build 15R5843a) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2017-10-16T17:05:27Z. The update package is 312.75 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: 3f675651943b4acadabd4025d0dfb421c03537aa.zip.