@LoneLocust
Green light good.
Red light bad.
No light bad/off.

It's really cool! Bright enough to indicate, but not so bright it lights up a room like a lot of other devices. (That's a pet peeve of mine.)
My one regret/mistake was I bought a USB outlet for one replacement, but the USB outlet only took 2 wires, and the box had 4. So, I installed that at the end of the circuit where the box only had 2 wires.