Product review (4 stars): this instrument has given me good service for a long time
I bought this about three years ago. It has worked well, but recently started defaulting to showing the temperature in Celsius rather than Fahrenheit.  There's a button on the back that lets you choose which temperature unit the monitor shows. If I push the button it will show the Fahrenheit reading again, temporarily, but it keeps reverting to Celsius. For the price, this instrument has given me good service for a long time, and I plan on buying another one.

As some reviewers have noted, the placement of the outdoor sensor unit is important. Don't place it in direct sun or the indoor unit will show inaccurate high temps.