iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone SE, released on 2018-04-24T17:11:17Z. The update package is 666.96 MB. This is a delta (partial) update that requires 11.2.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e66c12eba39db79b67b8d510116376391bf690cc.zip.