Battery operated erasers + Refills : This NE60 is just the best eraser with precision in erasing graphite and colored pencil. When the eraser is switched on the spinning action of the eraser lifts the pigment from the paper surface. This makes it ideal for correcting mistakes or re-working very small areas. The precise control offered by the eraser makes it suitable for highlighting. The eraser shape can be changed by working it on a spare piece of paper. A flat tip will give you a nice sharp edge which will erase a thin line . A round tip will allow you to erase a small dot. This eraser is designed as a drawing tool, for relining marks and amending small areas of your work. Revolution per minute: 14600 - 32000 U/min . Low weight and ergonomic design of eraser ensure pleasant operation and good control. It is perfect for left or right handed people and very comfortable to use. It takes 2 x AA batteries (batteries not included). Selective highlights can be created in already existing drawings.