Underneath the rear casing, we find a couple of snazzy battery eject levers—something we haven't seen in other controllers.

While battery eject levers are nice, what we're actually interested in is Valve's decision to abstain from using an integrated battery.

This design choice eliminates a commonly-failing component to extend the Steam Controller's lifetime, and gives users a choice: disposable or rechargeable batteries. The future of the planet is (literally) in your hands.