iPhone ipsw firmware download that provided by Apple, when you do the relevant operation at your own risk.
A1453 / A1457 / A1518 / A1528 / A1530 / A1533
11B511 · iPhone6,2
11B511 · iPhone6,1
11A501 · iPhone6,2
11A501 · iPhone6,1
11A466 · iPhone6,2
11A466 · iPhone6,1
11A470a · iPhone6,1
11A470a · iPhone6,2