To make sure the printouts are clear and legible, use black markers instead of ball-point pens to write the labels.
If no marker is available, black ball-point pens are allowed, although not recommended. Compared with ball-point pens, waterproof markers are better. When writing with a ball-point pen, do not leave the oil on the label, which may contaminate the label and blur the words.
The delivered marker has two nibs. Use the smaller nib to write the labels.