Thank you for viewing! This is a set of 13 check pens. These pens are convenient for memorization, as you can apply them over important words you want to memorize and then hide them with a sheet. - Brand: ZEBRA - Product Name: Check Pen - Colors: Green, Red, White - Quantity: Set of 13 There are 4 green pens, 3 red pens, and 6 white pens. How to use red and green pens: Mark the words you want to memorize, and cover them with the corresponding check sheet (red sheet for green marks, green sheet for red marks) to hide the text. How to use the white pen: Apply the white pen lightly over the red or green marks once or twice, and the marks will disappear within 5 seconds. You cannot overwrite the erased areas with the check pens. Although they are new and unused, please refrain from purchasing if you are concerned about personal storage.