Inside the slim barrel are four functions: black ink ballpoint, orange highlighter, 0.7mm mechanical pencil, and a PDA stylus. Each function is activated by a no-jam gravity feed: simply turn the pen so the icon for the function you want is facing upwards on the barrel, and push the button! To retract it, push the button on the clip. Refills available in the ACME Studio Accessories section, or by mail from ACME Studio (order form enclosed with pen). Remove the cap to find a white vinyl eraser underneath.