Pentel’s Ain Stein lead is made to be stronger and less susceptible to breakage than traditional mechanical pencil lead. These Pentel Ain Stein leads are in limited edition packaging celebrating the Pentel Smash. Available in .3mm or .5mm and your choice of case color: red, black, or gray. The cap is opened by twisting part-way to the side, so you will never lose it. Pairs well with the Pentel Smash Mechanical Pencil.