watchOS 5.1.1 (build 16R6600) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-11-05T18:05:53Z. The update package is 553.53 MB. This is a delta (partial) update that requires 5.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3b5c1d5a22f1def02becb691779bd905aeb24aad.zip.