watchOS 4.1 (build 15R5843a) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-10-16T17:05:58Z. The update package is 46.48 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3a62ab71f66d6ab9904955ccb8ce6bec08527361.zip.