watchOS 4.1 (build 15R5843a) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2017-10-16T17:06:00Z. The update package is 565.52 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: c6d421bd38d8e1cc68d8634a73b11fe1d3d03eb1.zip.