Preset CO2 control at 1500 PPM. Built-in self-calibration feature. Easiest to use CO2 controller on the market. Simply plug in your CO2 generator or regulator and you are ready to go. Built-in photocell allows CO2 enrichment only during daylight hours. Durable powder-coated steel enclosure. 15 Amps maximum/120 V/ 60 Hz. Patent No. D657,748.