EZ Reader Microhematocrit Card for ZipCombo Microcentrifuge (Catalog No. AP8212). After separating whole blood, determine whole blood to total blood volume using the EZ Reader Card. Place the EZ Reader Card on a countertop. Carefully remove one of the tubes and place it into the tube slot on the card and adjust the tube until the 0% line is aligned with the bottom of the fluid in the tube.