Arriving in China in 11 days in a bubble envelope, we must put the battery supplied to the back and tighten. The thermometer showed that 3 segments so I figured it was defective. I have not hesitated to tap a little (a bit much anyway!) And miracle all segments are displayed. The thermometer's rugged enough air and I think he had to take a hit during transport. 2 weeks it is in my aquarium, impeccable! On the packaging it says that accuracy is +/- 1 ° C. I can not compare the measure with another device but now I can see the water temperature differences. I recommend it for the price and I do not take away a star for the "wrong" announced precisely because anyway with heating tube in the aquarium water is probably not at the same temperature everywhere .. .