I bought 2 wireless thermometer from Wally World, the old on had a heat problem, the heat destroyed the lcd readout. I got home and discovered that all three read the same exact thing, even the one in the camper. I read the instruction and discovered that all three were reading the one under the carport, the distance is 165 feet. So the one in my reefer will not read correctly until I get on the road camping. unless I get a different brand. BTW they work wireless really good for reading the temp in the reefer without having to open the door. and for $9.88 they are a bargain the old one has worked for several years.