watchOS 4.3 (build 15T5165e) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-01-25T18:04:53Z. The update package is 320.86 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: 29e1a6a24c36c70473ce65e08f9fed639a6f2eb5.zip.