watchOS 5.1.1 (build 16R600) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-11-05T18:06:27Z. The update package is 763.86 MB. This is a delta (partial) update that requires 4.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9e2c1fc477b9f8709f33cf4cb9d16f8a9e0988b4.zip.