This refillable empty marker features a pump action valve which allows you to control 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. One end features a chiseled tip, great for creating shapes and lines and the other end features a rounded tip, perfect for small details or line work.Details:3mm tipDual-sided tips are replaceable,Empty markers do not work with metallics or neons