The MOCON OX-TRAN Model 2/61 is an oxygen permeation measurement system. Oxygen transmission through plastic foils or packages is analyzed in six independent cells by means of the carrier gas method. Each cell is sealed and consists of two parts which are separated by a plastic sample. One part is flushed with 100 % oxygen or ambient air. The other part is flushed with forming gas which serves as carrier gas. Oxygen which had permeated through the plastic, is transported to an electrochemical sensor responsible for the measurement. Oxygen Transmission Rate (OTR) can be obtained as a function of temperature in a range from 20°C to 65°C and as a function of relative humidity (RH) between 35 % to 100 %. Measurements are performed for plastic foils with a sample area of 10 cm² or plastic packages (like PET bottles).