watchOS 5.1.1 (build 16R600) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2018-11-05T18:07:02Z. The update package is 42.37 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1e1e2e0fcaa712c82187e3e3526008f321e0a8a0.zip.