This device has an LCD readout for both the temperature sensor inside the case, and a sensor on the end of a ten foot long wire. Thusly, it can function as both an indoor and an outdoor thermometer at the same time. I bought it for the temperature alarm feature, which can be set as both a high and low temperature alarm for both the indoor and the outdoor sensors. The unit does work as claimed, once you figure out the confusing instructions. Sadly, the alarm sound is so soft and tiny that the uses are limited. There are also some small lights that flash when the temperature alarm sounds. But, both the alarm noise and the flashing lights only continue for 5 second periods, once every minute. So, you'd have to be within just a few feet of the unit, or looking right at it to realize the temperature alarm had gone off, and you might have to be close by for up to a full minute to hear the alarm. The lack of a loud or noticable alarm severely limits the uses of this device. And since it's an LCD display, it cannot be read in the dark. I may find a use for this device as a thermometer, but it's not the alarm I needed.