What type of batteries does the CT3355 thermostat require, and how often should they be replaced?

The CT3355 requires two AA alkaline batteries; non-alkaline batteries do not last as long and can leak, causing damage to the thermostat or wall surface. Honeywell recommends Energizer® batteries. Although the thermostat has a low battery indicator, you should replace the batteries once a year to prevent the thermostat and heating/cooling system from shutting down due to lack of battery power. (Page 9)