Admittedly, you plus your son get 4 combined years out of the device. It's an unexpected way to count, but it works. And since you were talking about buying new

Admittedly, you plus your son get 4 combined years out of the device. It's an unexpected way to count, but it works. And since you were talking about buying new devices, I took it as a context where that's what the word "upgrading" means too. I wouldn't speak of open-source or third-party mods to the phone as "upgrades", just... "modding". Anyhow. Sorry for skimming.