This operating system is compatible with all iPhones from the 6s and 6s Plus models and newer. It is also compatible with these iPad models:
iPad Pro 12.9-inch (1st- 5th generations)
iPad Pro 11-inch (1st- 3rd generations)
iPad Pro 10.5-inch
iPad Pro 9.7-inch
iPad Air (3rd and 4th generations)
iPad Air 2
iPad mini (5th generation)
iPad mini 4
iPad (5th- 8th generations)