Pilot FriXion Purple Ink 0.5mm Erasable X-Fine Point Roller Ball Pens - 6 Pack Pilot FriXion Purple Ink 0.5mm Erasable X-Fine Point Roller Ball Pens - 6 Pack FriXion ball pens have a unique Thermo-Sensitive Gel Ink Formula that disappears with erasing friction. Erase and rewrite repeatedly without damaging any documents. 0.5mm Extra Fine point. Writes smooth, erases clean.