FriXion erasable ballpoint pen with retractable metal body type "FRIXION". BALL KNOCK Biz FriXion Ball Knock Biz is here! Once the head cap is removed, the rubber is embedded in the eraser. Rub your written text with the rubber and the friction heat will make the brush mark clear Since the ink is colorless using temperature changes, it is able to write and erase many times without erasing the ink. The matte metallic body is luxurious and goes well with business settings.