These little sensors transformed how my T9 thermostat manages temperatures. The setup was shockingly easy—pop in AAA batteries, stick them to the wall (though I swapped the tape for a tiny screw after one took a tumble), and pair via the Resideo app in under 5 minutes.

What blew me away? Motion detection. My home office used to feel like a sauna while the thermostat hallway stayed icy. Now, the system prioritizes whichever room I’m actually in. Night mode is magic too—it keeps our bedrooms perfectly cool without freezing out empty living spaces.

Pro tip: If pairing fails immediately, don’t waste time troubleshooting—exchange it. But when they work (like my three did), they’re spot-on accurate after a brief calibration period. The app lets me check humidity levels in the nursery, and I love watching the system adjust as we move through the house.

Battery life’s held up for 8 months so far, though I keep spares handy just in case. For uneven temperatures in older homes like mine, these are worth every penny of that $40 price tag.