The second major component of the Keck-CCAMS facility is a continuous flow stable isotope ratio mass spectrometer (Delta-Plus CFIRMS). The CFIRMS is interfaced with a Gasbench II (for CO2 or H2O stable isotope analysis) and a Fisons NA-1500 for 13C and 15N analysis. The CFIRMS can provide very precise measurements of stable isotopes (far higher than the precision provided by the AMS system). Such data can be very important to provide information on the carbon sources and pathways taken through terrestrial and ocean reservoirs.