This firmware is not signed. This means you cannot restore to it in iTunes.
| Release Date | 19 January 2016 |
| Upload Date | 12 January 2016 |
| File Name | iPhone4,1_9.2.1_13D15_Restore.ipsw |
| File Size | 1.48 GB |
| SHA256sum | 40a6100b6697dead0d60d2faf2260be304327fd7bcba78abed591aa03b3f469e |
| MD5sum | f43df8b54efb8808e65cedd7239c021d |
| SHA1sum | b6bd61a4ddb78bc65edc7d409de74bd6aa573e0a |
| Identifier | iPhone4,1 |
cd ~/Downloads.idevicerestore -e iPhone4,1_9.2.1_13D15_Restore.ipsw and press Enter.