Never used. Put a battery in one and read the installation manual only to find these units don't work with my heating / cooling units. They've been sitting in my garage for the last 3 years. Model TX500, which is selling on Amazon for $43 dollars each. First $25 takes them both. If you are reading this, the thermostats are still for sale. Email with a phone number, or call/text. Thanks for looking. Good luck.