Line lead sharpener - for 2mm leads. Set the length of the lead using the appropriate hole on the lid by opening up the clutch to allow the lead to drop to the bottom of the hole (if reasonably sharp use the left hole, blunt the right). Place pencil in the top cylinder, hold and circle round with it. You should feel a grating through the pencil as the lead makes contact with the metal grater within. Experiment with sharpness by further extending the lead. Use the sponge on top of the lid to wipe away dust (spare sponges are included with the sharpener).