The 30mm and 50mm Montana Acrylic Empty Markers are high quality manufactured refillable empty markers. The optimum flow control pump-valve system allows accurate handling and application. The transparent marker bodies allow for easy assessment of remaining marker content. Replacement tips are separately available. Perfect for use with the Montana Acrylic water based PAINT 180ml or 25ml. For optimal performance, we recommend using only Montana Acrylic Paint Refills with the Empty Markers. Screw left to open!