Honeywell Mercury- Round Thermostat the same classic round styling and footprint as traditional models but with a slightly taller design. This electronic thermostat is easy to install and use, providing precise temperature control for your home. It comes with a decorative cover ring that helps hide wall marks, maintaining a clean and polished look. Compatible with most single-stage heating systems, including hot water, gas, or steam, this thermostat is available in off-white and settings for heat only or both heat and cool options. Model Number: CT87K1004/E1