watchOS 4.1 (build 15R5823c) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-09-27T16:59:24Z. The update package is 226.89 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: ba9b5456a69f88845425d627eca81b87e3137bef.zip.