watchOS 5.0.1 (build 16R381) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-09-27T20:08:24Z. The update package is 963.72 MB. This is a delta (partial) update that requires 3.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 22400b99eb7f58059374e537b3360fa15b2cbc22.zip.