I’m not sure why you wouldn’t just use your built-in all-purpose moisture indicator (tongue) to tell whether your plant’s soil is dry, but this thing is cool anyway. It tests for wetness each second and blinks as your dirt dries out. They’re battery powered, and supposedly will last a year before you have to get a new power source. Ah, imagine a nighttime scene, just you and your best girl sitting on the lawn, watching a constellation of blinking LEDs signaling that their host plant is shriveling up like an old lady. How romantic!