1.DoubleTip Design: The black tip of larger pen is for shadowside transition, and the white tip is for transitioning halftones into light and dark sides or blending light sides; the black tip of smaller pen is for details handling, making your sketch more dynamic and visually appealing. 2.Suitable Size: Our blending sponge pens come with 2 sizes to meet your different needs. The larger pen has a nib diameter of approximately 0.47 inch/1.2cm and a total length of 5.9 inch/15cm; the smaller pen has a nib diameter of approximately 0.29 inch/0.75cm and a total length of 5.51 inch/14cm. 3.Reliable Material: Made of sponge, felt and plastic pole; the black tip is made of sponge and the white tip is made of felt, helping smoothly blend different sides. The sturdy plastic pole makes them longlasting and comfortable to hold, washable and reusable. 4.Package Content: You receive 6 pieces of blending pens in 2 sizes. The quantity is sufficient for your use and art classes. The white felt tip may contain some black wool but it doesn't affect the actual use.