A method and system that enable the measurement of a second-harmonic-generation-forwardbackward ratio from an object by performing only a single image scan using via epi-imaging using an epi-detection technique. The connector includes a seat member with an opening for receiving an anchor bolt that secures the connector to the second building structural member. The CO2 monitor may measure CO2 gas flow rate or pressure, and indicate excessive CO2 gas consumption if the measured CO2 gas flow rate is above a predetermined flow rate or the measured CO2 gas pressure is below a predetermined pressure level.