No bells and whistles, just connect your CO2 generator and you're set! This is Grozone's beginner solution for growers looking for affordable and easy-to-use CO2 controller. User can select from five pre-set CO2 control values (1000, 1125, 1250, 1375 and 1500 ppm). User can select from five pre-set elevation values for improved CO2 control in higher altitude (sea level, 1000, 3000, 5280 and 7000 ft). 3-LED display shows ambient CO2 value (7 ranges between 899 and 1601 ppm). Day/night detection to turn off CO2 enrichment during the night. One-button calibration in fresh air (400 ppm). 5-Amps Output (for CO2 burner valve or regulator coil).