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 136.69 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: b1631b880b2ccf7aa1a44c81f0cce24db4c0b5cc.zip.