The Pumper Valve Action Paint Marker - Yellow - Valve Assembly: The patented valve assembly is a spring loaded device that supplies a measured portion of paint to the nib when pressed. The Shell: The heavy gauge aluminium shell can take abuse, and is designed to survive in a rugged industrial environment. The Cap: Unique shape that prevents from rolling away. Easy twist-off. Stores on the end when in use. Clean Up: Cleans up easily with Xylene, paint thinner, or other similar solvents. This is a permanent marker, and will permanently stain some surfaces