Review on hygger 50W Mini Submersible Digital Display Aquarium Heater: Compact, Fast Heating & Thermoregulation for 🐠 Small Fish Tanks, with External Controller & Built-in Thermometer - Ideal for Betta and Turtle Tanks by Gelin Battle

I don't know how accurate it is but it seemed to respond quickly to the addition of cooler or warmer water and my fish were happy. A few days ago the LED read "HH" (meaning 95+ degrees) so it went off. Except that the water was actually only 68 degrees. It scanned up and down between 87 and HH as if it couldn't figure out what the temp was, then switched to HH for a while before it started scanning again. I was very happy with it until it happened. Less than 6 months is totally unacceptable reliability. UPDATE: Support responded to my email within hours and sent a new heater free of charge. Thanks to this great review I've upped my rating because it's definitely worth a try as the heating works so well.