Pilot Frixion series is the best erasable pen on the market. Pilot makes it with advanced technique on ink. You can easily erase your mistakes with its thermo sensitive ink. The special pilot ink technique - when temperature reach the point, ink becomes transparent automatically by rubbing with the rubber at the end of the pen. The change of the ink is based on the change of temperature and won't leave any dirt.
This Pilot Frixion ball knock gel pen is retractable and refillable. Please note because of the thermo sensitive ink, it may be not suitable for important mails and documents.
There are also Pilot Frixion design series and various color for you to choose from.