E Instruments Combustion Analyzer model BTU1500-1Like new, only used a 1/2 dozen times. E Instruments 1500-1 Combustion Gas Analyzer/Environ Analyzer - Style (Gas Detection): Hand-Held,Combustion Analyzer with built-in printer for O2, CO, CO2, Efficiency, Excess Air, Draft, Pressure. Includes: Memory, PC Software, Wireless Bluetooth, probe, hose, case, charger, Auto Calculations for High Efficiency Systems, downloadable ANDROID & APPLE APP<CO, CO2, Combustion Efficiency, Excess AirBUILT-IN PrinterFull COLOR Graphic DisplayOutdoor Air Temp Measurement & nbsp(High Efficiency &; Condensing Boilers)PC Software w/ Auto Saving; pre-Calibrated Field Replaceable Sensors; 2000 Internal Test Memory;5 Tools-In-One;Ambient CO Monitor;Built-In Pressure ManometerDraft & Differential Pressure Flue & Ambient TemperatureZoom FeatureUnbreakable Metal ConnectionsHigh Efficiency Kits AvailableIncoming Temp (High Efficiency & Condensing Boilers)32 Fuels & Oils (Including Bio-Fuel)ONE Button Operation