The mechanical pencil is well known today throughout the world, largely thanks to Sharp's founder Tokuji Hayakawa. By developing an original lead-thrusting device and inserting it into a metallic shaft, he revolutionized one of the world's most convenient devices. At the time there was another mechanical pencil available, but it was made of celluloid and was very awkward, aesthetically unappealing and too fragile for everyday use. Using his knowledge of metals and metallurgy, he improved upon the construction and appearance of the existing device and in 1915, produced a mechanical pencil made of nickel. The "Hayakawa mechanical pencil" was patented and marketed as the "screw pencil" or "propelling pencil.