Atlas® 1 CO2 Monitor/Controller comes with a 25 foot remote sensor. It features adjustable set point and elevation levels, a built in 'self calibration' function and an integrated photocell that enables operation in daytime hours only, when the plants need CO2. Simple to use and easy to operate. 15 Amps/120 Volt/60 Hz. Replacement sensor can be purchased separately. The sensor comes factory calibrated for precise CO2 readings and utilizes low voltage technology to avoid Radio Frequency Interference (RFI) from electronic ballasts. Sensor has 90 day warranty.