watchOS 5.1.3 (16S5531a) for Apple Watch Series 4 (40mm, LTE) ✗ This OTA is not signed. OTA firmwares cannot be restored to. IPSW Downloads collects them for
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Release Date December 19, 2018 Upload Date December 17, 2018 Filename 5eaf585c4a80c85df92912594ee4d4c28a128e60.zip Filesize 1.4 GiB Identifier Watch4,3
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