There's a real problem that affects almost all mechanical pencils—bear with us as we explain. As you use a regular mechanical pencil, the lead wears down on one side, forming a slanted wedge-shaped tip. Each time you put the lead to the page you end up using a different lead surface (pointy, flat, wide, thin) depending on how you hold the pencil. This can cause dramatic and unsightly variations in line thickness as you write or draw. eleminates this problem with the use of an ingenious lead rotation mechanism that continually rotates the pencil lead as you write. A spring-loaded clutch twists the lead incrementally every time you lift the pencil from the paper. This allows a uniform wearing of the lead to create a conical tip shape that provides a fine, consistent line. The knurled grip ensures a slip-free hold of the pencil. The capped eraser is refillable. The nose cone of this pencil is metal.