The refill set of 3 Frixion Ball 4 from Pilot with the lead thickness 0.5 mm (line width 0.25 mm) is suitable for the pen Frixion Ball 4 (2268). The lead colour is black. The ink is thermosensitive ink that disappears when heat is influenced and reappears when the cold is influenced. The ink is removable by friction and can be overwritten.