PAP Pen is designed to provide a water repellant barrier when a circle is drawn around mounted tissue on slide, it is suitable for Immunohistochemistry, fluorescent staining and traditional chemical staining, the barrier of the PAP PEN retains solution within the defined area and ensures, that only the amount of solution needed for sufficient reaction is used, the designed multi-size tip (1 mm and 4 mm) of the Hito Aqua Barrier PAP Pen is especially useful when working with multiple small sections or one big section on a single slide. The water repellent circle is insoluble in alcohol and can be removed if desired by xylene after the staining procedure.800 circles / Pen