Four Gas Analyzer Model SY-GA 401 Four Gas Analyzer Model SY-GA 401 Measuring Item : CO, HC, Co2, O2, » ( air surplus rate) , AFR, NOX ( optional) Measuring method : CO, HC, Co2 : NDIR method O2 NOX: Electrochemical Cell Repeatability : Less than ± 2% FS Response time : Within 10 Seconds ( more than 90% ) Conection to PC : by RS 232 port