Honeywell CM927 CM921 CM727 CM721 CMS927 Replacement unit the older versions
The Pro Series Wireless Programmable Thermostat will replace the following Honeywell CM Series products: CM921, CMS921, CMS921B1042 CM927, CMS927, CMS927B1049 CM727, CMS727, CMS727E1016 CM721, CMS721.