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 one among five preset CO2 control values (1000, 1125, 1250, 1375, and 1500 PPM). User can select one among five preset 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).