HemoTemp monitors only show what the temperature of the blood unit is at the exact moment that you look at the indicator. It cannot tell you the history of the blood unit. If there is no color in any of the windows then the blood unit is above 12 degrees C or below 0 degrees C. The interpretation of the indicator is based on the color of the numbers. See the HemoTemp product bulletin for more information. The HemoTemp monitors are used for shipping and indicate temps up to 12 degrees C. Whole blood and pRBCs should not be stored long term at temps above 4 degrees C. Anything above this will significantly reduce viability and shelf life of the product.