S4500-2

S4500-2 (2-Gas) Kit: O2, CO, CO2, Built-In Printer, CO Dilution Auto-Range up to 100,000 ppm, Upgradeable to a 3rd or 4th Gas Sensor, Combustion Efficiency, Excess Air, Draft, Differential Pressure, Temperature, Calculations for High Efficiency and Condensing Systems, 12-inch Probe with 10-inch Hose, and Hard Plastic Carrying Case