iOS 5.1.1 is a legendary version for the iPhone 4S and iPad 3 because it was the last version easily jailbreakable on those devices for many years, and it is the target for "Downgrade" tools developed around 2021. If you are looking for tools released around 2021 to mod or downgrade iOS 5.1.1 devices (specifically the iPhone 4S and iPad 2/3), these are the most significant IPAs. Lumion Pro 10.5.1