watchOS 5.1.1 (build 16R600) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-11-05T18:06:26Z. The update package is 763.87 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4d05d99ea36161d56e3fe4a9446f45d533bdb4ab.zip.