The uniquely formulated, water-based ink will not bleed through paper, and the non-squeak, bullet tip is designed to deliver a superior marking performance. The low odor formula is perfect for office or classroom settings. Bright, vivid colors are an instant standout on flip chart paper or presentation boards. Four distinctive colors make a brilliant statement. Water-based ink formula will not bleed through flip chart paper or presentation boards. Complies with Prop 65.