It is sad as the outdoors unit is fairly accurate but the probe is useless.  If there was a linear difference between the probe's reading and the hot tub thermometer then fine, I could deal with that, ie, add two degrees, etc.  but alas, there isn't.  For example, when the hot tub is running and showing a temperature of 103, the probe might be showing 105.3 or 104.6 or 104 or who knows.

Update.  The probe now shows OFL no matter how long it  has been inside the house.  I have replaced batteries, reconnected..etc.

Don't waste your money
It is sad as the outdoors unit is fairly accurate but the probe is useless. If there was a linear difference between the probe's reading and the hot tub thermometer then fine, I could deal with that, ie, add two degrees, etc. but alas, there isn't. For example, when the hot tub is running and showing a temperature of 103, the probe might be showing 105. 3 or 104. 6 or 104 or who knows. Update. The probe now shows OFL no matter how long it  has been inside the house. I have replaced batteries, reconnected.. etc. Don't waste your money