Uni Jetstream 4&1 Multi Pen - Ghibli StudiosUni Jetstream x Ghibli Studios Multi Pen Four ballpoint ink 0. 38mm (black, blue, green, and red) 0. 5 mm mechanical pencil The ballpoint components feature Uni's revolutionary low viscosity Jetstream inkfamous for its smooth ink flow, quick drying times, and water and light resistance. They also feature a special spring mechanism that prevents ink leakage, plus a twin ball in the back of the tip to prevent backflow. Eraser underneath the top cap.