This furnace incorporates two stage operation (high/low output) with a variable speed blower motor. The multistage feature provides you with quieter operation, more even temperatures throughout the home, reduced temperature swings between heating cycles, reduced draftiness, more air filtration for better indoor air quality, and less stress on the furnace for greater component longevity. The variable speed fan motor is more electrically efficient when compared with non-variable speed fans, and will operate at a greater number of speeds than either the single stage or two stage. And the furnace circuit board has more feature-rich software, so that when it is combined with Bryant’s Evolution series thermostat, you will have many features you would otherwise not have (e.g., continuous fan speed control, a diagnostic alert system to indicate when there’s a problem with the furnace and what it is, WiFi, etc.). If you want the best within the standard efficiency group, this is the choice.