A mechanical pencil is one that requires no sharpening as the lead point can be extended mechanically.
1Uni-ball Kurutoga Mechanical Pencil Starter Set

The 0.5mm lead points of the Uni-ball Kurutoga Mechanical pencils can be extended easily using their patented lead advancement mechanism. The mechanical pencil offers a sharp lead point for crisp writing and highly detailed technical and artistic drawings. With their sturdy diamond-infused lead points, they are not as susceptible to breakages as most 0.5mm mechanical pencils are. You are guaranteed of a continuously sharp point, thanks to the self-sharpening rotating mechanism of this mecB0026ICM1Ehanical pencil. The complete starter set includes a mechanical pencil, one pack of lead refills and two eraser refills.