I'm asking about a wall mounted heating control thermostsat.

What is your question, did you loose the instructions? Try this for a manual http://yourhome.honeywell.com/home/Applications/SmartSearchResults.aspx?searchkey=rth221b#expand/collapse

Thanks for the help. Called customercare, they had the answer. It wasn't in the guide.

No RTH221B1021 does not have a backlight