Empty marker. The Montana ACRYLIC EMPTY Marker 50 mm is a high quality manufactured refillable empty marker. 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. For optimal performance, we recommend using only Montana ACRYLIC Paint Refills with the Empty Markers. Screw left to open.