Pentel’s AIN STEIN 0.5 B graphite lead for 0.5 mechanical pencils. 20pcs included in case. Made in Japan.

STEIN stands for "Strongest Technology by Enhanced SiO2 Integrated Network". These enhanced silica leads feature a reinforced silica core that makes these leads smooth, strong (less breakage), and sharp. This lead is designed to be smear resistant, so you can have smudge free and clear writing. Lead technology is amazing now!