Parsec MOX Systems are the only systems currently available that measure oxygen by weight. All Parsec units utilize a micro- processor chip programmed with the formula PR=nRT which is calculated 16 times per second. Parsec units never need to be calibrated and self- compensate for temperature and pressure variation. All units are extremely reliable, user friendly and accurate. A program dose CD comes with all units as well as lifetime technical support. Multi units feature digital display, are PC compatible and keep history that is printable.