ZEBRA ZEBRA 3 green pens and 3 red pens Check Pen Green and red check sheet My son used these when he was studying for his entrance exams. I've tested all of them, and they all work without any problems. The check sheet is used, so it has some scratches and wear, but I'll include it as a bonus. These are used items, so please refrain from purchasing if you are sensitive to such things. Thank you. Thank you for looking.