tvOS 8.1.3 (build 12B466) is an official Apple over-the-air update for the Apple TV 3 (2013), released on 2015-01-27T17:55:03Z. The update package is 120.03 MB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 14bee9330a6a9dc5932491db13c44bb70d100636.zip.