These refillable markers feature a pump action valve which controls the flow of the paint. Empty markers can be filled with your color choice of Angelus Acrylic Paint mixed with Angelus 2-Thin (1:1 ratio). Most colors will require adjusting with 2-Thin in order to flow right. Does not work with metallics or neons. The replaceable tip is also reversible. One end features a chisel tip, great for creating shapes and lines and the other end features a round tip, ideal for small details or line work. Angelus Empty Paint Markers are available in 3mm and 5mm.